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The accept (and, as far as i know, "back") buttons cannot be disabled under any configuration where a user is able to access a task assigned to more users than just themselves. As Stefan said, "accept" is absolutely essential since there's no other way for a particular user to take ownership of that task instance.
The "reassign" control can be disabled by setting the Task Reassignment Permissions to "none", though I should caution you that if you view a task as a System Admin user, you'll still see it (though basic users won't).
can you please tell me where the Reassign Permissions Setting Will be available
in the "assignment" tab of the task:
"set re-assignment privileges for assignees"
change to "no privilege", which will be the desired setting for individually-assigned basic-user tasks in almost all cases (other settings can be explored when the users in question are more power-users and/or group-assigned, but that's out of scope for now).
Thankyou Very Much @ Mike Schmitt