This depends on the state of the package.
1. Has an active maintainer? They must go to the package's repo, and in the settings,
grant you commit/admin access. [1]
2. Has a maintainer, but they're inactive? You must fire up the non-responsive
maintainer policy. [2]
3. Package is orphaned, but not retired yet? Go to the repo and just click the
"Take" button. [3]
4. Package has been retired? File a ticket with releng. If it's been retired for more
than 8 weeks, you'll need to re-submit it to Package Review. [4]
I think that's all the possibilities, unless I missed something.
A.FI.
[1]
https://src.fedoraproject.org/rpms/${PKGNAME}/settings
[2]
https://docs.fedoraproject.org/en-US/fesco/Policy_for_nonresponsive_packa...
[3]
https://docs.fedoraproject.org/en-US/package-maintainers/Package_Orphanin...
[4]
https://docs.fedoraproject.org/en-US/package-maintainers/Package_Retireme...