Access phone without entering SIM PIN I have a SIM card completely stuck in the SIM slot of my old phone so it's asking me for the SIM PIN every time which I do not know. Opening a Samsung S6 to access the SIM-slot on MB is not the easiest thing so I'd rather not...

How can I close down the SIM PIN prompt to get into the phone?

I do know the PIN of the phone but not for the SIM

Phone: Galaxy S6
In order to unlock you need PUK(Personal Unblocking Key) code. If you have your SIM card kit, that was given to you when you purchased your SIM card then you might find PUK code on that. Since you pointed out that your phone is old so you might not have PUK or SIM kit, in that case Contact your carrier for PUK, they will ask you some details which varies carrier to carrier.
Then you have to block you PIN by entering it wrong multiple times(5-10 times) and you will be asked for PUK code. Remember, if you enter incorrect PUK code 10 times you SIM card will be blocked and you will get a message SIM card registration failed.