How do I double spend using electrum for fix unconfirmed transaction

Question

I have two Blockchain.com wallets.(Both of them are mine)
Some days ago i did a big mistake.
I sent 1100$ From wallet #1 to wallet #2. (10.0 sat/vB > As you see this is very very low) (TX LINK)
And i sent that 1100$ to my friend from wallet #2 after the transaction upper immediately. (99.3 sat/vB) (TX LINK)
Because of low fee in first transaction, both transactions have n't confirmed yet.
I asked people to fix these unconfirmed transactions.
They told me use another wallet like Electrum wallet and double spend those unconfirmed transactions.
So i installed Electrum in my windows 7 os.
For double spend using electrum i found this link :
https://steemit.com/bitcoin/@profitgenerator/tutorial-how-to-fix-unconfirmed-transactions But it seems it has deprecated.
I could n't understand one part of this tutorial :

Re-create the transaction, but this time put a higher fee.
Sign your transaction, and save it to a file, it should end with .txn extension

My questions :

1. As you know Blockchain.Com has no RBF option. So those two transactions have n't RBF flag. In this situation can i use double spend with electrum?
2. How can i create a transaction in offline mode and sign and save it?
   I tried it.But after setting fee and click send button electrum tried to broadcast.And i could n't find an option for sign or save transaction with .txn ex.
   Would you please share a complete step by step tut about this.
3. If i double spend first transaction what happen to second unconfirmed one? (I am a bit confused about this)
4. Should i double spend two unconfirmed transactions with two temp wallets in electrum or double send of first one is enough?