Disintegration, fire and any solid projectile (wand or throwing weapon) will clear them but it takes some seconds for the visual effect to fade out. The web is gone after the missile hits it, just watch for it to fade. If I don’t want to use a wand on them I just keep a stack of missile weapons on a quick slot to throw at web tiles, this destroys them and costs no durability. Fire will spread through webs like grass too so be careful, or use that to catch multiple enemies and burn them.