Quick answer: Wipe a sound silicone bead with warm water and mild soap, then dry the seam. If the silicone is cracked, lifting, soft, or dark throughout, surface cleaning will not restore the seal. Check the cabinet below for moisture and stop if the sink or counter is leaking.
Inspect the joint before cleaning
Look along the front edge, back edge, corners, and around the faucet base. A healthy bead should stay attached to the sink and counter with no open channel. Pressing hard on the silicone is not necessary; visual gaps, movement, or water collecting beneath the rim are enough reason to investigate.
Open the cabinet below and check for dampness, swollen particleboard, stains, or a drip trail. A dark line above the sink can be a symptom of water getting where it should not. Cleaning the visible edge without checking below can leave the real problem untouched.
Clean a small surface mark gently
Remove crumbs and loose residue with a soft cloth. Use warm water and a small amount of mild soap on a non-abrasive cloth, then wipe along the bead instead of scrubbing across it. Rinse the cloth often and dry the area completely.
Do not combine bleach, vinegar, ammonia, or other cleaning products. Avoid cutting into the silicone with a knife or using an abrasive pad that can open the edge. If a labeled cleaner is appropriate for the sink and seal, follow its instructions and test a small area first.
When the seal needs repair
Caulk that is detached, split, or darkened through the bead usually needs removal and replacement. The joint must be clean and dry before new sealant is applied, and the replacement product must be suitable for the sink and counter materials. If you are not sure whether the counter is stone, laminate, wood, or another finish, check its care guidance first.
Stop and get help when water is reaching the cabinet, the counter has swollen, the leak continues, or the damaged area is extensive. A surface clean is useful maintenance; it is not a substitute for a sound waterproof joint.
For nearby plumbing and residue checks, see the under-sink guide. If you are working through several kitchen surfaces, use the order described in Clean First, Then Disinfect.