RPM allows each user to have one thousand active views per section of RPM. This includes built-in, shared, and private views. If you receive the warning that the custom view limit has been reached, views no longer used will need to be deleted. 

On the section of RPM, you have received the error, click the drop-down list for View.

Review the list of views you have access to. When you find a view you no longer need, select the view to load it. 

With the view now loaded, click Edit beside the views name. 

In the edit view screen, click More at the top and select Trash

Repeat these steps with any other outdated views.