Currently we can only delete repositories from Repository Settings or using API. It will be good to have an option to delete repositories from "Project Settings" page since this is a blocker while deleting a project.

Workaround:

• API to get list of repositories for a project

  curl -u <username>:<app_password> -X GET "https://api.bitbucket.org/2.0/repositories/{workspace_name}?q=project.key+%3D+%22<<ENTER YOUR PROJECT KEY>>%22&pagelen=100"
  

• As a next step you may iterate the list of repository to delete API provided below

  curl --request DELETE \
    --url 'https://api.bitbucket.org/2.0/repositories/{workspace}/{repo_slug}' \
    --header 'Authorization: Bearer <access_token>'
  

  or

  curl -u <username>:<app_password> -X DELETE 'https://api.bitbucket.org/2.0/repositories/{workspace}/{repo_slug}'
  

  Source: https://developer.atlassian.com/cloud/bitbucket/rest/api-group-repositories/#api-repositories-workspace-repo-slug-delete
  Reference for app_passwords: https://support.atlassian.com/bitbucket-cloud/docs/app-passwords/