It is okay if you added a location to a custom group (Entity Tag) that should not be there. You can remove any location from entity tags with no hassle. From the Manage Locations section click on the Bulk Actions button.

When the drop down menu opens, select Manage Entity Tags.

From there you can select any Entity tag listed.

Once selected, simply click the trash icon to remove the location from this entity tag.

If you want to undo this process, simply click on the Add button in the upper right hand of the window. From there, simply type the recently deleted locations store code and press Save. The location is now included in the custom group (Entity Tag) until changed.

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