Mass deletion of SAP roles from users

Hello All,

i need to delete all assinged roles from a big number of users. I know the users but not the roles which the users have. I need to delete all roles from the users-id's.

I know SU10 and i can select all my needed users. But in the role tab i can not work with roles-names like Z* to delete. I can select all z*-roles and select "remove" but when i click to save, i get the message no changes made on the users???

Any idea?

Gruß

Toni