Had battery test full 12v on test, had starter cleaned and rebuilt I don't have a seat safety switch, so I'm thinking the soleniod. How do you bypass the soleniod to see if that's why my mower crank

Bypassing safetys can hurt or kill.
Be sure if you bypass, have out of gear, but treat as being in gear, in case starter engages.
Not sure your model, but most have 2 terminals, when it receives a ground through the safetys, and a hot from the start switch, it engages. Restore safetys.

You can use jumper cable to go from one big post on the solenoid to the other big post and see if it cranks. It will spark when you hook the second cable. But, this will tell you if the starter is OK. If it cranks take the jumper from the battery side of the solenoid to the small post on the solenoid and see if it cranks then. If it does then the solenoid is good.

If you don't have current going to the small post on the solenoid you will need to trace the wire from the ignition switch to the solenoid to see why.

If you Use a Large Cable, connect to Starter first, then other to Battery Positive to keep from welding on your solenoid threads.