Metro PCS how to unrestrict tethering?

Hello! First thanks in advance for taking the time to look at this post! Brand new android user here, please realize that i know NONE of the phone lingo, i have no idea what i'm doing, if you decide to help please explain any and ALL steps required. I hear it's possible to bypass the Metro PCS tethering cap of 6GB included in the unlimited data plan(60$) and use the phone's data instead, would someone please do me the favor of telling me how? :)

Phone: Samsung Galaxy Core Prime
Model #: SM-G360T1
Android Version: 5.1.1

PS: Looking to get my hands on a NEW, UNUSED, UNLOCKED Galaxy s5 (Black only) for 330$ or less, if anyone happens to know where i could get one id appreciate that info as well :)