Do I need to reinstall localhost?

A Trojen horse is not good to have in your computer. I hope you properly removed it. Yes! You should remove the trojen horse, so you made a good choice. If you reinstalled your operating system on your hard drive, then you would have to reinstall Wampserver with WordPress, and Joomla.

People say there are other ways to remove infections from a computer, but in my opinion, I think the best option to remove a trojen horse is to reinstall the operating system on the hard drive.

I recommend you start over, and you reinstall everything on your computer. Make sure you don't infect your computer with something!

Anti-malware programs are usually good enough that complete reinstalls are unnecessary!

When you say you "removed it", what do you mean by "it?"