how can i force a parameter and remove force value in ABB FREELANCE 2000 SERIES IN AC 800F CONTROLLER
Not sure what you mean with forcing a parameter and it is also not clear a parameter of what object?
If you want to temporary change a parameter of a function block, you can open the configuration dialog of the function block in commissioning mode. Put in the new value and select "write". Do NOT select "correct".
With "Write" the value is written to the controller, but the engineering database still has the old value. To indicate there is a difference, the background of the parameter input field will change to yellow. You can switch between "Configured Values" and "Current Values" with the buttons in the dialog. It is a view switch only, not a switch in the controller.
To change the value back to the old value, switch to "Configured Value", note down that value, switch back to "Current Value" and change it to the value you noted down for "Configured Value". Then press "Write again". The yellow background will disappear and their should be no longer a difference between "Configured" or "Current" value.
Tip: If it is too cumbersome to first note down the old value and then enter it manually, you can close the parameter dialog and switch to configuration mode. Then you open the dialog again, which will show you the original configured value. Here you can copy it. Close the dialog, switch back to commissioning, open the dialog and paste the configured value into the parameter field. Then write it down to the controller.