Cleanly strip cracked or moldy caulk from a tub, sink, or window so a fresh bead will seal and adhere properly.
Silicone caulk peels easier when softened. Apply a commercial caulk remover gel or rubbing alcohol along the bead and let it sit 2–3 hours per the product directions. For latex caulk, a heat gun or hair dryer on low held a few inches away also softens it.
Use a utility knife or a dedicated caulk-removal tool to slice along both the top and bottom edges of the caulk bead. Angle the blade away from the tub or tile surface so you cut the caulk, not the finish. This frees the strip from both surfaces it is bonded to.
Grab one end with needle-nose pliers and peel the loosened strip out in one continuous pull when possible. Scrape away any remaining bits with a plastic putty knife or an old credit card to avoid scratching the surface.
Wipe the channel with rubbing alcohol or mineral spirits to remove every trace of old silicone — new caulk will not stick to leftover residue. If there was mold, scrub with a bleach solution, rinse, and let the joint dry completely before applying fresh caulk.