The "Location" field you see in the configuration console under Lansweeper\Scanned Devices is the same one that can be found on individual device webpages.
To change device "Location" information, go to the device's webpage and hit the "Edit device details" button. Make your changes and check the "lock against scanning" checkbox. Then hit the "Save changes" button.
You could also bulk edit this field for several devices by running a script in the Lansweeper configuration console under Lansweeper\Database Scripts.