H1B Stamped - Can employer Cancel the petition

USA H1B Visa
1

My H1B has got stamped and after that I have resigned from the Job and not working currently.

Will my previous employer can cancel my H1B petition?

If they have not cancelled the petition how long I have option to transfer my H1B to another employer.

In Case it is canceld Can I use the cap exempt quota through the another employer?

2

If you find another employer, they can file a new petition under cap-exempt anytime within 6 years (in case of fresh H1B and you haven’t spent time US) of first H1

3

What LionKing mentioned holds true even after the employer withdraws the petition.