On my mountain bike, which has Presta, I simply break the bead and pour the liquid into the open tire, reseal and inflate as normal. Quick, easy and while still on the bike.
On a Schrader valve, you must take the valve out and use a hose to squeeze the liquid into the tube. Then, reinstall the valve and inflate. Again, while the tire is still on the rim and bike. No need to remove anything other than the valve. Many caps have a notched molded tip for this reason, if not, the tool is cheap and readily available most anywhere.