Changing the 'Group' of an item in Bestiary

[NielsenE]

I'm not sure what I did but a custom monster I was adding, got added to the group 'PF2 Bestiary' instead of uncategorized. How do I move it out of the PF2 Bestiary group?

[Zacchaeus]

Click the drop down at the top so that the group you want to add the beastie to is visible and then drag the beastie from the bottom window and drop it onto the group you want to add it to.