Caulking is one of those projects where it is not always necessary to use the entire cartridge to complete your project. The remaining caulk tends to stay in the caulking gun until it is needed again. This being the case, you may go quite some time before you need to use the caulking gun again. Once the need arises, a caulk that is different from the one in the gun may be necessary. To use the new caulk, you must remove the old cartridge from the gun.
Place a cap on the end of the existing caulking cartridge, or insert an object such as a nail into the opening to prevent any remaining caulk from leaking out during removal.
Press the release lever on the back of the caulking gun, and pull the plunger back to remove it from the cartridge. The release lever is usually a small lever located just above the pistol grip of the caulking gun. You can identify the plunger by the L-shaped metal bar sticking out of the back of the gun.
Lift the cartridge out of the gun once the plunger is fully retracted. Wipe down any residue present on the gun before loading a new cartridge to ensure that the new cartridge fits in properly and to make removal easier.