Under Advance Settings > Advanced Options...you can check the box to "Automatically quarantine detected items"
In v1.75, PUP detections show up unchecked on the results list by default and you have to manually check each one for removal. If you want Malwarebytes Anti-Malware to remove PUP detections, each item must be checked. If provided a lengthly list of PUPS to check and remove, to do so quickly, you can highlight one of the detections by left clicking on it. Then, right click on the highlighted detection, and select 'Check all items'. Next, click Remove Selected. See Selecting all PUPs for removal