Hello and
Glad you like Malwarebytes, it is definitely the best in malware protection and removal.... That being said, if the items are already in the quarantine, you can leave them there, they in no way are active and can no longer cause problems with your computer unless you were to restore them. I tend to leave items in my quarantine for a while to make sure there was not a false positive and something was removed that was needed. (no one is perfect and mistakes do occur from time to time).
I may empty the quarantine after a few months pass by and I confirm my system is working without issues.
Either way its a matter of choice, but once you have removed it from the quarantine tab, there is no going back.

Dell Precision T7500, Win7 Ultimate 64bit fully updated, McAfee Corp Edition v8.8,
Watchguard Firewall, Intel Xeon E5606CPU, Dual Quad Core Processors, 16GB Ram,
E5606 @ 2.13GHz, Nvidia Quadro NVS420, Raid-1 Dual 1TB Sata 10000 rpm Hard Drives
Dual DVD Burners, IE10, Opera, MBAM