Clara. It may depend on the reason given for needing to change it. Was it due to having been published before elsewhere? That is a possible trigger for needing to change a hub. If the reason is unclear, you can ask Hubpages about it. That way, you'll know more exactly what you need to change about it. If, as someone else suggested you just 'unpublish it', you won't have to delete the whole hub. You can fix whatever is the problem with the poem, and then publish it again. Your title won't be affected. However, when you unpublish a hub, there may be a time limit to republish it. You need to pay careful attention to any instructions given with it. It may be that it is only deleting a hub that carries a time limit.
You are in a great situation to become more computer wise! It's by doing things that one does learn more. But I must warn you, if you are concerned with how much time it takes in the learning stages, - well -- good luck. I've been using computers for 23 years and online for 14 of them - and I'm still learning every time I sit down -- and sometimes, when I'm stumped - I may have to sit here quite awhile to muddle through and figure it out. But it accummulates and each step takes you further and 'keeps' in your information and expertise bank.
Glad you're here in HP - and, trust me, it will be worth the effort and time! Hugs - Nellieanna