Yeah, I know there's an addon to do this easier, but this is the already integrated vBulletin way.
You can do this two ways.
First way:
Let's say it's this thread:
Tick the little box on the right, then it'll show like this:
Notice the change in color.
Then, scroll down and find this:
On the Options, select "Move Threads" like this:
Then Press Go.
Second Way:
Go to the thread you want to delete, like this:
Then, see where it says "Thread Tools" like this:
Then tick "Move Thread" and press Perform Action.
Now this is for both steps:
The next page, make it look like this:
Press Move Threads, and your done! :D
You can do this two ways.
First way:
Let's say it's this thread:
Tick the little box on the right, then it'll show like this:
Notice the change in color.
Then, scroll down and find this:
On the Options, select "Move Threads" like this:
Then Press Go.
Second Way:
Go to the thread you want to delete, like this:
Then, see where it says "Thread Tools" like this:
Then tick "Move Thread" and press Perform Action.
Now this is for both steps:
The next page, make it look like this:
Press Move Threads, and your done! :D