Per Backup your Hosted Data: About Hosted Data:
All Bitwarden data is stored on the host machine in the
./bwdata directory, relative to the location in which you installed Bitwarden.
If the goal is to reset all the config and stored data to redo that, then stopping Bitwarden and deleting the bwdata directory will remove any config-related data allowing one to follow the installation guide again to configure it again from scratch.
This will leave any docker images in place though, so it does not fully reset it to a fully pre-install state, but would allow for a fresh start in terms of setting up and configuring Bitwarden.
I agree with OP though, an “uninstall” command for bitwarden.sh would be nice to reset everything, including docker, back to a pre-install state.