PUP stands for Potentially Unwanted Programs. These are programs our researchers have found are sometimes added to a system without the user's knowledge or approval.
In Malwarebytes Anti-Malware versions 2.0 and higher, PUPs are set to be quarantined by default. This can be confirmed in Settings > Detection and Protection > Non-Malware Protection.
If you want Malwarebytes Anti-Malware to remove PUP detections, each item must be checked.
To select more than one item, click the check box in the top row next to the Threat label, then click the Remove Selected button.
If Malwarebytes Anti-Malware is detecting a program as a PUP that you use and wish to keep, you can prevent it from being quarantined, refer to KB article, How to configure exclusions with Malwarebytes 3.