Short Answer

You don’t.

Long Answer

These two plugins are fundamentally different. Popular Posts stores views in a custom field with each post. Top 10 creates a new table in the database and stores views there.

So you’ll need to look for the wp_top-ten table in your database. It should have these fields:

• postnumber
• cntaccess

postnumber is the ID of your post and cntaccess is the number of views it has. You can move this into the pvc_views custom field for the post to migrate the data.

You’ll likely need to script this in SQL; that’s an exercise I leave to you. In reality, you’d be better served just switching to the new plugin and starting your counter from scratch.