Your question is not clear for me. Are you trying to perform a bulk update of the Location information?
Which version of NPM are you running?
Thanks in advance for detailing further.
If you are tring to update this field for multiple nodes at once, you can try the following in NPM 9.5:
Connect to the web console as an Admin.
Click on Admin > Manage Nodes.
Select multiple nodes and click on Edit Properties.
Scroll to the bottom and edit the Custom properties for the nodes selected.
Click on Submit.
I forgot to add that the Location information is by default retrieved by SNMP.
So if you wish to update this value, reconfigure the SNMP agents on the monitored devices.
If you are instead using a custom property, the previous post could help.