Another app is currently holding the yum lock

Hit Ctrl-C; that's the key combination to kill any currently running process in a bash shell or terminal.

To find out what's locking up yum, try running:

# ps aux | grep yum

Note the PID number of the process and run this to kill the process:

# kill

Check to see if the process has been killed by rerunning:

# ps aux | grep yum

If not, rinse and repeat until the process is killed; some processes can be very stubborn