The app that cannot be uninstalled
Once this app’s plugins are placed on a site, the app cannot be uninstalled.
Wix refuses while any plugin is still placed:
This app has visual elements on your site. To delete it, go to the Editor. After deleting, publish your site so changes go live.
And there is no way to carry that instruction out for every piece.
The SDK has a call to place a site plugin and no counterpart. Nothing can unplace one programmatically. The dialog that call opens looks like it can — it shows a “Remove from Side Cart” heading — but those are column labels describing a Replace, and its only actions are Replace and Cancel. And checkout cannot be edited in the Editor at all, so a plugin placed there is unreachable by the route the message points at.
So the honest position, stated in the app’s own documentation and on the website: treat installation as one-way. Before installing on a shop that matters, decide that it is staying. If it ever must come off, Wix Support has a route that is not exposed to apps.
In development, never uninstall. Create a fresh development site whenever a clean install is wanted; they cost nothing and take seconds.
The shop’s data is independent of all this either way. Bookings, settings and appearances live in ordinary CMS collections on the site itself, so they survive whatever happens to the app.
Writing that on a marketing page is uncomfortable. Not writing it, and having a shop discover it, is worse — and it would be discovered at exactly the moment they had already decided they did not want you.