I would like to go from hot storage (electrum wallet) to cold storage without modifying my private key and seed phrase.
First you need to have cold storage device ready with clean operating system, this could be hardware wallet or separate offline computer/laptop without any internet connection.
You can even generate paper wallet cold storage using offline computer I preciously mentioned, but easiest solution for newbies is to use open source hardware wallets like Trezor, Bitbox, Passport or Keystone.
Simply sending coins from your hot wallet to address generated by new cold wallet will be enough.
Is it enough if I delete my electrum wallet on my macbook ?
No.