Trojan.Agent refers to a generic Trojan malware detection. It is used for detections that are either associated with no specific malware families or not enough information is available to pinpoint the malware family.
Rogue.ForcedExtension is the detection for Chrome extensions that are forced upon users.
The extensions are forced upon users by sites using browser lock scripts. You can read more about this procedure in our blog post, Forced into installing a Chrome extension.
Malwarebytes can remove the extension, but users may have to remove the file manually under Tools > Settings > Extensions. Remove the tick mark and click the bin icon behind the offending entry.