I restored a new project onto a linux PC. I'm writing values from Edge Historian to a csv file. The thing is I'm seeing tags for the previous project? Is there a way to clear all of these out?
Tags aren't part of the project - they are part of the gateway.
You aren't seeing the tags from the previous project - you are seeing the tags for the gateway which has not been updated.
If you want the tags from the other gateway (where the project was exported or backed up from) then you need to export the tags from it and import them to the new gateway. The same applies to other gateway scoped items.
As for the tags currently in the tag provider, if you really don't plan to use them anymore, you can just mass-select and delete them. I strongly recommend doing a tag export before you delete them, just in case you or someone changes their mind later.