Use this trick to bulk delete repos in an organization

bulk-delete-repos-org.md

Bulk delete repos in an organization

Remove all repons in an organization

USERNAME="joeangel"
PASSWORD="YOUR PASSWORD"
ORG="THE ORG name"
curl -u $USERNAME:$PASSWORD "https://api.github.com/orgs/$ORG/repos?page=1&per_page=100" | jq '.[].full_name' | tr -d '\r' | xargs -I '{}' curl -u $USERNAME:$PASSWORD -XDELETE https://api.github.com/repos/'{}'

Remove all repos exclude which name including the string gitlab in an organization

USERNAME="joeangel"
PASSWORD="YOUR PASSWORD"
ORG="THE ORG name"
curl -u $USERNAME:$PASSWORD "https://api.github.com/orgs/$ORG/repos?page=1&per_page=100" | jq '.[].full_name' | tr -d '\r' | grep -v 'gitlab' | xargs -I '{}' curl -u $USERNAME:$PASSWORD -XDELETE https://api.github.com/repos/'{}'

The part grep -v 'gitlab' meas: ignore the repos which name including the string gitlab

References

• Use this trick to bulk delete your old repos or old forks - adamvoss commented on 12 Mar 2018
• Pagination - GitHub developer