As Wouter indicated, the easiest way if you want clean permanent grouping by location, you can set that up by default.  If you use IDP (DataMiner Infrastructure Discovery and Provisioning app (IDP) - DataMiner Dojo), you have structured management of all locations, buildings, racks, floors, etc.  If you disable the auto-grouping, you can right click on the headers of multiple columns in the Alarm Console and also do layered grouping (e.g. group on location and then by rack). 

The option Tobe mentioned is definitely also something everybody should be looking into.  Of course that is a more dynamic grouping, where DataMiner will make a assessment of which alarms are likely to be related to the same incident.  And if alarms occur at around the same time, on devices hosted in the same rack or location, then indeed they are more likely to be related to the same incident (and hence they are more likely to be grouped automatically by this capability).