Developer goodies: the delete all module to clean up thousands of nodes
When you want to delete a lot of nodes or users you can use the delete all module in drupal. You have some handy drush commands:
drush delete-all article Delect all article nodes. drush delete-all all Delete nodes of all types. drush delete-all --reset Delete nodes of all types, and reset node, revision and comment counters. drush delete-all users Delete users. Options: --reset Reset counter for node, revision and comment tables. --roles pick roles Aliases: da
As you can see you can delete nodes by type, users by role.
You can even reset node counters. but then you must delete all nodes.
There is also a quick method available which does not use node_delete but deletes everything with a single SQL statement. Performs a lot better.