"resmgr:cpu quantum" means the resource manager is doing exactly what is has been asked to do - control access to resources.

You see this event when the box is under strain to the extent that we need to be able to guarantee sufficient resources to whatever services you have defined as high priority. Other sessions that are consuming excessive resource (in this case CPU) are forced to 'sleep' aka 'resmgr:cpu quantum' so that critical services get a slice of the CPU.

Yes you could turn off resource manager by resetting 'resource_manager_plan', but all that means is that whatever session(s) are consuming all of your CPU now have no throttling applied, so they might stop other sessions from getting the resources they need.

I would like at *why* your box is under strain - tackle that first.