Cryptocurrency Wallet Seed - mental backup? Ok, so let's say I use a wallet that gave me a 12 word string as a seed.

And I want to do a paper and "mental" backup - will write it down and will memorize the words.

Where is the itch? 
Well, the seed file that my wallet created is still on my disk and exposed to hack danger.

If I deinstall the wallet and delete the seed file - am I more safer than?

And I won't have any issues using the seed with other wallet when I choose to use my cryptos?
Uninstalling the wallet will not make anything more secure. Deleting the wallet also does not guarantee that the wallet file is gone; it is usually still on disk for some time after it has been "deleted". You will be exposing your seed to a computer anyways any time you want to send Bitcoin and get new addresses to be receiving Bitcoin at. By only remembering your seed, you may be a little bit safer than if you had let the wallet do its thing (where it encrypts the wallet file and is still on your computer). I don't think you will actually a significantly more secure. All you are doing is just increasing the risk that you lose all of your coins (by forgetting the seed) and making it more of a hassle to send and receive Bitcoin.


  And I won't have any issues using the seed with other wallet when I choose to use my cryptos?


Not all seeds will work with other wallets or altcoin wallets. It depends on how addresses are derived, what standard the seed follows, etc.