Remove outdated plugin from IPB

I get this error when trying to remove a plugin from my ipb forums

2S119/1 The CSRF protection key did not match. This may indicate a plugin or theme is out of date. Please contact technical support for more information.

I tried deleting all data associating with the plugin via the admin cp but it keeps giving me this error, anyone know how to remove an outdated plugin? For now it's disabled but I would like to remove it