Use the soldering iron to gently heat the top tab while at the same time using the tweezers to pull the top tab away from the board

Then do the same to the bottom tab until the battery is free, be sure no to heat the board too much and only where it is soldered

Install the new battery in reverse order heating the solder first then setting the tabs on the hot solder, a little more solder may be needed to hold it in place, once it is cool check that the battery is secure