Restrict the SUS vendor changing own data

Hello SUS Experts,

We are on SRM 7 EHP 3 and customer wants to restrict the change access to Suppliers to change his own data.

We already provided z roles to the suppliers only administrator can only change the data of supplier and assignment of roles.

Problem: Administrator --> OWN --> Click on Process button --> Edit screen appeared --> he can able to change the password & able to assgin the roles.

We want to restrict this above activity. Would like to provide him only display access.

I believe this can be restrict through roles in PFCG. What authorization object to restrict the OWN Data.

Thanks in advance!!!

-Anil