You need some sort of pdf editing software, the most "famous" being Adobe, at great expense.
There are others, some free, and there have been a few recent posts on the subject. They all offer some editing abilities, but whether they will be good enough for you, only you will know!
One is click here
Another click here look around there is a free trial you can download.
I'm looking at some of them myself, but so far, none of them meet my requirements; they may be OK for you though.