The [x]([GUID]) component cannot be deleted because it is referenced by [y] other components. For a list of referenced components, use the RetrieveDependenciesForDeleteRequest.

When you get this message, then you can find the dependencies through a webservice call. If you don't have a programming environment available, then it can be hard to find out what causes the delete to be cancelled. For instance, when the component isn't easily accessible through the CRM UI. For on-premise solutions where you can access the database, it's pretty easy to find out what is the dependent component. Just run the stored procedure:

exec p_RetrieveDependenciesForDelete '[GUID]' [ComponentType]

for example:

exec p_RetrieveDependenciesForDelete '37BB549F-8D9A-E511-80D3-005056BB2FDF', 52

The Guid is mentioned in the error message, just copy this into the query. The Component type can be found here: