Hex Mapping (Tomb of Annihilation Roll20 Actual Play)

How did Adam do the hex exploration stuff on his map?

The map is built with all of the hexes in the official Roll20 module.

Just started watching them, are the white hex’s removable like tokens?

yep in the official roll20 module for TOA  the blanked hex's on the player map and just tokens you can delete or move to the gm layer as needed to reveal the full map underneath (to the same end any land marks/ points of interest in the covered area are on the gm layer for you to move to the token or map layer as needed (though if your sending them to map make sure to send the actual map "to back" so it doesn't accidentally cover them))

cool thanks