Renaming of folders is not supported through the web UI.
However, you could run a Move Item REST query that will move artifacts from a specific path to a different path in the same repository. For example:
curl -X POST -uadmin:password "http://localhost:8081/artifactory/api/move/libs-release-local/org/jfrog?to=libs-release-local/org/<otherfolder>"
NOTE: If you have maven artifacts then the move operation of pom files will fail with a 409 error. To avoid this issue, please change the pom's maven coordinates to match the new folder name.