If someone else has ownership of the drawing, project, or individual pieces or equipment and they are not in the office or near their computer. Here are the steps.
Open Revit, but NOT a project.
Click the big R on the upper left
Under general menu, you will see the user name as being yours. Change the user name to their user name. Make sure you know their user name.
Open the project now that has the issues, you will be using their user name since you switched it. Click on the collaborate tab, and click relinquish all mine.
After save to central.
Next close out of the project.
When you are done and no longer in a project, click the big R again, and change the user name back to your own user name.