If you disable venues with LR the following will happen
You won't see them on your site
They won't be held against a match in the admin
You won't be able to use the advanced scheduler and some other scheduling programs e.g. the conflict checker
Go to Setup > Settings > then in League Options you'll see another tab called Venues, click on this.
Then check the box to disable venues from being shown and used within the admin and the league website.
Any league that gets setup as "Gaming" will have venues disabled by default. This can be changed if required.