Only a few steps are necessary to disable advertising. You can do this by signing up for an ad-free subscription, which is provided by the respective app store. Therefore, make sure that you are logged in to the store with the correct account.
Follow these steps to turn off the ads:
1. Launch the Rummy app.
2. Open the menu (flat arrow)
3. Select the settings (gear icon)
4. Select the tab “Game” at the top of the screen
5. Tap on "Yes" next to the item ADVERTISEMENT
6. Choose between one of three options - 1, 3 or 12 months - and confirm with "Okay".
7. Confirm your purchase again for the App Store.
If the ads do not disappear immediately, restart the app and/or follow the steps above to point 4 and tap "Restore subscription" in the ADVERTISEMENT menu. This renews the connection between the store and the app to be renewed.
If you still see ads, you can find more information at "Why do I see ads even though I'm subscribed?"
At the moment it is not possible to disable the ads in Rummy Multiplayer.