vector - How do I delete the center of the letter A in Adobe Illustrator CS5?

I need the center of the letter A in Illustrator to be transparent so you can see the background underneath. Same with letter D, B, O, P, R.

I imported a vector version of a word, and I am able to select the letter but if I click delete button it deletes the whole word.

Answer

Select the letter and its counter (hole) and choose Object > Compound Path > Make.