The URL for any challenge is editable via the Administration > General Settings > Setup Settings panel of each community/challenge. This means that selecting a URL during the challenge creation process is an editable option after challenge creation.
Please note that the option is restricted to the challenge or community domain and does not permit amendments to the main domain. For example in the URL below, the highlighted green element (challenge1) could be edited via this new tool:
Community and challenge names appear at the end of the URL instead of at the beginning of it:
You can access all IdeaPlace links from these URLs.
For platform administrators, when creating a new challenge or community, you will see this URL structure in the challenge wizard: