Since this was a OOB field and hence cannot be customized.

we couldn’t hide/remove those Activities Type as they are not usual views, they are part of System tailored Activity entity family (Activity, Activity Pointer, Activity Party, Custom Activity types, etc).

I would like to remove some of the Activity Types because they are irrelevant for the application and the users have requested them to be removed.

It would be useful to be able to hide the Activities filter to make it easier for users.