To delete a custom page part:
1. Go to /admin/pageparts/custom.aspx
2. Select the trash can icon next to the Custom Page Part you’d like to delete
3. You’ll be given the option to Permanently Delete all Instances or to Convert All Instances to a Stand Alone Matrix
If you choose Permanently Delete all Instances , all instances of the Custom Page Part along with the Custom Page Part itself will be permanently deleted. If this Custom Page Part was a Core Custom Page Part, it will no longer appear in the list of potential Core Custom Page Parts.
If Convert All Instances to a Stand Alone Matrix is selected, the Custom Page Part will be deleted and all instances will be converted to stand alone matrices with the same configuration as the Custom Page Part.