Product version -
6.5 Update 6
Problem statement –
Manager Unable to close and finalize till and Getting Error "Cannot Close other user till"
Proposed solution/workaround –
Check if user is manager, Check security role if user can finalize till and if user is closing his own till.
Steps if any -
Go to Employee-->Open the concerned employee-->IsManager checkbox should be checked, in case you want to remove the till of any user

Constraints/scenarios - Only manager can remove other user till in case till mode is user.