How to remove grid format object GFxxxxxxx in OMW default project folder?

We are in the process of upgrading JDE to 9.2 with tool release 9.2.4.4. I notice that there are a lot of the GF objects in my default project folder in OMW. Unlike the other objects, such as the batch or interactive app, etc., as soon as I click on the GF objects, the buttons in the middle of the OMW disappear, so I cannot remove the GF objects from my default folder. I tried to move the GF objects to another project folder, but that did not work either. Is there a way to remove them? Thank you in advance.