That's a standard issue. When you re-login from RF device, it will not prompt you to log off other sessions.
First solution
Put the ABAP code in the custom RF transaction to unlock based on override.
To do this I have manually tracked it via control table to ensure the user doesn't accidentally kill/unlock the active sessions. This is kind of a recovery mechanism to pick up from you left off.
I have successfully done this.
Second Solution
I have found this one to work but it is not practical.
Login in from the desktop or laptop and when you get the prompt to logoff other session, select it to kill other open sessions.
Third Solution
Develop a custom program with tcode put it on the RF Menu.
The custom program will check if the user has any open sessions and kill it.
Use FM TH_USER_LIST to get the list of users, filter it on the current user and use FM TH_DELETE_USER to delete sessions.
Do note, it will also kill the current session on the RF device.
This will unlock the transaction records.
As step 2, re login.
Fourth Solution
Reduce the timeout on sessions. This is controlled by basis.