The question is a bit old, but in case it can help someone else, here is what I did to disable SSISDB Catalog.
In SSMS go to Integration Services Catalogs folder, right click on the SSIDB catalog and choose Delete.
It will drop the catalog, drop the SSISDB database and drop the maintenance Job.
It will allow you to re-create/re-enable again in the future if needed.
English is not my native language... so, you know... sorry in advance 😉