Let's get this straight. You are asking how to set up a TV but you have not told us the make and model?
If you could tell us the make and model, we could search online for the manual, look up how to change demo mode and, if it's possible without the remote, to reply. We'd probably make a pointed comment that you could have tried searching for the manual yourself.
We might have also sugg Syed you find someone with a similar TV and see if you could borrow their remote, especially in the event that you can only change do mode with a remote.
Heigh ho
January 2020