Deadheading is a weird term for simply removing the spent flowers, or dead heads, from a flowering plant. Removing the dead heads keeps your gardening looking tidy and encourages new growth.
Using a pair of clean, sharp secateurs, gently cut the dead and dying blooms from its stem.
You can discard cut flowers. If you have a compost pile, throw the dead heads in!
I grow Snowcap Shasta Daisies in my garden - see how much better they look?
New blooms will start to show up in a couple of days.