If you are trying to enable the AD Recycle Bin on Windows Server and the feature is grayed out in the AD Administrative Center, it’s either already enabled, or the Forest Functional Level isn’t at Windows Server 2008 R2 or later.
Check if the feature is enabled by using the following PowerShell command.
Get-ADOptionalFeature -Filter 'Name -like "Recycle Bin Feature"'
Not already enabled: EnabledScopes will be empty “{}”…
Already enabled: EnabledScopes will not be empty…
Assuming you’re able to raise the Forest Functional Level do so, and then proceed to enable the AD Recycle Bin feature as detailed in another of my posts (click here).