I've upgraded to a newer version of a WordPress plugin that has some bugs.

I want to get rid of it and reinstall the old version.

Fortunately I have a copy of the old plugin running in a test directory setup.

To reinstall the old plugin, can i simply -

1. deactivate the new plugin
2. delete the new plugin directory
3. copy and upload the old plugin folder to the /plugins/ directory
4. activate the new plugin

Any problem with that or do i need to drop MySQL tables as well?

It depends on the plugin, I would try it without dropping the tables and if there was a problem drop the tables and do a clean reinstall.