Hi thanks for the response. How exactly do I
just need to spend one of the inputs to that transaction to make it invalid and then you can be sure it will never confirm.
Is that a feature in Electrum? Or is that a feature any wallet can do?
Some other wallets will let you do it as well but as I use Electrum it is the one I can explain how to do it with.
Goto View > Show Coins
From the newly displayed Coins tab select the input(s) you want to use with right click and 'spend". Then fill in the normal transaction details, you can send it to yourself using another address in the same wallet if you want. Obviously, use a high enough fee for it to confirm.
Also before you start on Electrum go to Tools > Propose Replace-By-Fee and select Always, then you never end up in the situation you are now.
Can you please explain? I have waited for my transaction to be dropped from the network, bit it does not seem that is the case. Is there a time frame that this will happen under?
Timeout settings for dropping transactions are individually configurable for every node on the network. Many nodes will have already dropped it. Any node can rebroadcast a transaction if it wants to so it is not predictable or even guaranteed it will totally disappear, but it usually does at some point.