How can I remove a carrier from my iPhone?

You will need to contact the carrier that the phone is locked to and ask them if they will unlock it. They are the only ones who can.

How to unlock your iPhone for use with a different carrier - Apple Support

Fihrtn wrote:

Please tell me how can I get rid of the old operator and install a new eSIM I have some restrictions on installing a new SIM it says contact the operator but I do not have access to this operator

I hope you are not telling us that you "do not have access to" the phone company (carrier) who placed the carrier lock on the phone. Only that carrier can remove the carrier lock.

Where did you buy the new phone? If the new phone was carrier-locked at purchase time, I would hope that the retailer who sold it to you would be able to at least identify the carrier.

You might consider returning your “new” phone for a refund.

Your prospects for getting this particular device to work w/ your carrier are fairly poor.