There is no option for requesting a different custom url at this time, If you are unhappy with this process, please send Feedback (in the left-hand drop down menu). The team looks at each and every piece of feedback sent in, and the more feedback they get on a particular topic, the more this becomes a priority.
To activate the Feedback Tool type an @ symbol outside of a text entry area, or click on the link at the bottom of the left side menu. https://support.google.com/plus/answer/1678224?hl=en-GB
If you want additional details regarding Custom URL’s, then please see the following Help Center article:https://support.google.com/plus/answer/2676340?hl=en