Unable to remove project number from project name

Love the ability to sort by project number.  Thanks for implementing that.  We are having a problem editing the names of our existing projects now.  We used to put the project number in the name so we could effectively sort.  Since we don't have to do that now i would like to remove the project number from the front end of the project name.  Is there a cache file somewhere we need to purge or refresh or something to get these project names edited?  

Here is a screenshot of what the project name looks like now....

And then the message we get when we try to rename (just removing the "17623" from the beginning of the name)...