Simply connect the device to Ledger Live, select "Manager", follow the instructions regarding unlocking and allowing Ledger Manager access...
Then delete the BTC, ETH and Stellar apps from within Ledger Manager. (Click the trashcan button).
Once the are all removed, simply reinstall each one by clicking the Install button in Ledger Manager
Removing and reinstalling the apps on the device will not cause you to lose any coins.
In fact, as long as you have the 24 word recovery seed mnemonic (and any added BIP39 passphrase), you can wipe the device completely and still recover all your coins... As you'll be able to restore the seed that ALL you wallets are derived from.
and you can start with any app.
That isn't strictly true... You have to install BTC before you can install any BTC derivatives (DOGE, LTC, BCH, BTG etc)... And there are ETH derivatives that require the ETH app installed before you can use them.
There is a list of BTC and ETH dependent apps here:
https://support.ledger.com/hc/en-us/articles/360021026973-Smaller-Ethereum-app-now-available-in-Manager