Hi Udeesha,
For context: by setting an eCPM floor, you're instructing the AdMob Network not to serve ads to that ad unit that are below the minimum eCPM you've set. You can theoretically "turn off" ads by setting the eCPM floor to an impossibly high number (as was suggested in the second link you provided).
That being said, I would advise against using this if you could rather edit your app's code directly, since eCPM changes take time to manifest, especially if the ad units are new; you can check the "Inaccurate floors in new ad units" section from this page for further details. It may also lead to a prolonged period of having no-fills on your ad units once you turn the eCPM floors back down.
If you still want to go through changing the eCPM, then you may do so via your AdMob console. Kindly see attached screenshots for further details on this.