Newed
3
The question is, do you really need the order to always remain sequential (no missing numbers) when items are removed? Because if that’s not the case, you wouldn’t even need to worry about it.
But if you really need this, depending of the amount of records in the list, you could follow the suggestion above or use some approach like the suggestion below, before remove the record:
1 - Use the action Make changes to a list of things
2 - Then set the list RG's List of things :items from # Current Cell's Index or in cases when the RG may have some filters applied to it maybe you need to set the list directly from the Database to avoid issues. In this case you could use Do a search for {Select Thing} and then set the constraint Order > Current Cell's Order.
3 - Update Order field to Order = This Thing's Order - 1