Cannot change event selections to remove price field in price set when sold out
When using a price set for an event registration with a max participants limit for a specific price field, once that price field reaches the limit, it isn't possible to remove the contact from that price set field from the backend. It just shows sold out and doesn't allow you to remove the contact. This works the same if it is a checkbox or numerical value, etc.
Presumably, this is to prevent contacts being added to sold out events, but it should be possible to remove them from sold out events. The price field should only be disabled if the contact isn't registered for it. It should be enabled if the contact is registered, so that it can be removed. This would be more complex in the case of numerical value fields, but this would at least fix the issue for checkboxes, radio selects, etc.
Tested on demo on Drupal (5.14.alpha1) and 5.7.4 on Drupal.