You are able to delete or mark queries as inactive from Admin > Query Maintenance
This will display all of your available queries (not including the Vega preset queries) with some options for you to make changes:
The search bar will allow you to easily find a query by its name.
Queries can be selected by clicking the checkboxes on the righthand side and then you have the options to delete or deactivate the selected queries, this can be done in bulk or one by one.
There is a checkbox at the bottom of the screen which will allow you to see any inactive queries and you have the option to re-activate these if needed.