Oh boy, if you’ve gone and lost the key you have three options:
Contact the manufacturer to request a replacement.
Go to a mechanic (and be prepared to drop a fair amount of money).
Get a socket wrench that just fits over the lock. Hammer it on and then very slowly unscrew the wheel lock.
Clamp locks are easier, just cut one of the clamp arms off with an angle grinder or a power tool with a metal cutting blade attachment.