H1B Visa revoke/ withdrawal

Hi, I am currently in India for last 4 years. My H1B is currently expired however I have 1.5 years of period left on my H1B visa. My I-140 is also approved in 2019.
I want to change my employer from employer A to employer B in India. Could you please let me know if after joining the new employer (B) can I transfer my H1B to B in future when I want to travel to US with them after some time? Also, Please let me know does employer A need to withdraw H1B once I left even though it’s currently expired?

Yes however technically it wont be a transfer but a fresh cap-exempt H1B petition files by employer B.

Once you leave any H1B employer, they have to withdraw your H1B by law.

Thanks @Kalpesh_Dalwadi. My current H1B is expired and I have been in India for last 4 years. In that case also does my current employer will have to withdraw the H1B?

They should have withdrawn at the time you left the H1B job. When I say left the H1B job, you may still be employed with the same employer outside of the US but that is not H1B job. H1b only applies when working within the US, so once you leave the US you are no more in H1b status.