Craig.
I went through the exact same thing a few days ago and was getting the same error as you initially. As well as removing the tables you need to remove the plugin. You all need to remove the templates you added to merge buddypress from wordpress. It’s one of these templates which causes the not found error as the template is looking for buddypress in the plugins directory.
Remove the buddypress tables via phpmyadmin, deactivate the plugin (and delete it if you wish) and then delete all the templates you uploaded. You should be fine after that.
