functions/Remove-DbaDbCertificate.ps1

function Remove-DbaDbCertificate {
<#
    .SYNOPSIS
        Deletes specified database certificate
 
    .DESCRIPTION
        Deletes specified database certificate
 
    .PARAMETER SqlInstance
        The target SQL Server instance or instances.
 
    .PARAMETER SqlCredential
        Allows you to login to SQL Server using alternative credentials.
 
    .PARAMETER Database
        The database where the certificate will be removed.
 
    .PARAMETER Certificate
        The certificate that will be removed
 
    .PARAMETER WhatIf
        Shows what would happen if the command were to run. No actions are actually performed.
 
    .PARAMETER Confirm
        Prompts you for confirmation before executing any changing operations within the command.
 
    .PARAMETER EnableException
        By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message.
        This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting.
        Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
 
    .PARAMETER InputObject
        Piped certificate objects
 
    .NOTES
        Tags: Certificate
        Author: Chrissy LeMaire (@cl), netnerds.net
 
        Website: https://dbatools.io
        Copyright: (c) 2018 by dbatools, licensed under MIT
        License: MIT https://opensource.org/licenses/MIT
 
    .EXAMPLE
        PS C:\> Remove-DbaDbCertificate -SqlInstance Server1
 
        The certificate in the master database on server1 will be removed if it exists.
 
    .EXAMPLE
        PS C:\> Remove-DbaDbCertificate -SqlInstance Server1 -Database db1 -Confirm:$false
 
        Suppresses all prompts to remove the certificate in the 'db1' database and drops the key.
 
#>

    [CmdletBinding(DefaultParameterSetName = "Default", SupportsShouldProcess = $true, ConfirmImpact = "High")]
    param (
        [parameter(Mandatory, ParameterSetName = "instance")]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstanceParameter[]]$SqlInstance,
        [PSCredential]$SqlCredential,
        [parameter(Mandatory, ParameterSetName = "instance")]
        [object[]]$Database,
        [parameter(Mandatory, ParameterSetName = "instance")]
        [object[]]$Certificate,
        [parameter(ValueFromPipeline, ParameterSetName = "collection")]
        [Microsoft.SqlServer.Management.Smo.Certificate[]]$InputObject,
        [Alias('Silent')]
        [switch]$EnableException
    )
    begin {

        Test-DbaDeprecation -DeprecatedOn "1.0.0" -Alias Remove-DbaDatabaseCertificate

        function drop-cert ($smocert) {
            $server = $smocert.Parent.Parent
            $instance = $server.DomainInstanceName
            $cert = $smocert.Name
            $db = $smocert.Parent.Name

            $output = [pscustomobject]@{
                ComputerName = $server.ComputerName
                InstanceName = $server.ServiceName
                SqlInstance  = $instance
                Database     = $db
                Certificate  = $cert
                Status       = $null
            }

            if ($Pscmdlet.ShouldProcess($instance, "Dropping the certificate named $cert for database '$db' on $server")) {
                try {
                    $smocert.Drop()
                    Write-Message -Level Verbose -Message "Successfully removed certificate named $cert from the $db database on $server"
                    $output.status = "Success"
                }
                catch {
                    $output.Status = "Failure"
                    Stop-Function -Message "Failed to drop certificate named $cert from $db on $server." -Target $smocert -InnerErrorRecord $_ -Continue
                }
                $output
            }
        }
    }
    process {

        foreach ($instance in $SqlInstance) {
            try {
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $sqlcredential
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }

            foreach ($db in $Database) {
                $currentdb = $server.Databases[$db]

                if ($null -eq $currentdb) {
                    Stop-Function -Message "Database '$db' does not exist on $server" -Target $currentdb -Continue
                }

                if (-not $currentdb.IsAccessible) {
                    Stop-Function -Message "Database '$db' is not accessible" -Target $currentdb -Continue
                }

                foreach ($cert in $certificate) {
                    $smocert = $currentdb.Certificates[$cert]

                    if ($null -eq $smocert) {
                        Stop-Function -Message "No certificate named $cert exists in the $db database on $server" -Target $currentdb.Certificates -Continue
                    }

                    Drop-Cert -smocert $smocert
                }
            }
        }

        foreach ($smocert in $InputObject) {
            Drop-Cert -smocert $smocert
        }
    }
}