There are two ways to unlink Twitter currently:
1. Revoking access for Vero on Twitter website https://twitter.com/settings/applications
2. Revoking access for Vero in the Twitter app in settings (Connected Apps)
Relink will happen automatically through a pop-up when you share to Twitter again.
Eventually, we hope to have a switch in Vero to make this more convenient but until then, this is the workaround.
Thank you for using Vero!