Unlock Table Maintenance generator

Hi

I have created TMG for customized table. In that i have selected maintenance type as one step. Now i want to change this as two step. But when i am changing the table (se11->tablename-> change ) its in change mode after that when i am trying to change TMG (utilities-> Table Maintenance generator ) it is showing one message 'Object components locked in different tasks'. How to unlock this.

please help me