Unable to remove asserted mass property value at top level assembly

Unable to remove asserted mass property at the top level assembly.

From the screen shot below, we can see that the selected component contains an asserted mass property/value and is being used in the From Design under the Source column.  This indicates that the asserted mass property was applied at the part level, so the component must be opened in its own window (Open in Window) to change the Source from Asserted to From Design.  Changing this will clear the Asserted icon, and a green check mark will appear at the top level assembly and component level.