Hi Tufail,
You can remove all roles using SU10 by following below steps.
01. Insert all 700 users in SU10 User tab
02. In roles tab, enter all roles assigned to users which you wish to delete.
03. Enter 01.01.1900 Start Date & 31.12.9999 End Date.
Start date should be the earliest Role assignment start date amongst all users - 1, so that all roles assigned are captured in the date criteria and removed completely.
03. Select Remove from Roles and Profile's Tab and Save.
04. If you are performign this activity in CUA, please check SCUL for unprocessed IDOCs.
Regards,
Atul