Hi @Michael Lam ,
Currently you cannot change the url in cloud instances and there are couple open requests with Atlassian for same.
Please refer below Atlassian documentation for more details.
@Michael Lam , like Avinash said, you can';t currently Change the URL but it is coming! Take a look at this Atlassian Doc for more information:
it looks like you only option until they get this done is to create a new site and then migrate.
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