Do you have shrubs and flowers, growing closer and closer together, with grass growing in between? Killing grass at this point would be a great way to make this one large bed. But you picture physically picking out the grass and possibly damaging root systems of these established plants right?
Killing grass can be done without back breaking labor. You just need a bit of time and effort, but not back breaking work.
Save up all your newspapers for a week or so, depending on how large the area is that you are dealing with. Get rid of any colored comics etc. Try and have it black and white newsprint as much as possible for killing grass.
Trim the grass between the shrubs and flowers and whatever plants you have growing, using garden clippers. Don't use the electric or gas trimmers as they can damage the plants going in that close. Just use the manual clippers and get the grass as short as possible. Killing grass is much easier if it is short and clipped.
Get a load of mulch handy. Depending on the size of the area where you are killing grass, you can get mulch in bags or you can get it delivered by the truck full. Simple basic mulch not the fancy bark.
Try and pick a calm day, and you should have some help with this. Take your newspapers and open them out and layer at least 3 layers together of newspapers, and lay them on the grass right up to under your shrubs and plants. Not climbing up the plants but as close to the root area as you can to start killing grass.
Cover the entire newspaper area with 4 or 5 inches of mulch. Edge your garden, it will look wonderful right now! Instant garden bed. The newspaper will eventually compost into the ground but will be killing grass and turning it back into the soil as it breaks down. Colored comics don't break down the same way, so that is why when killing grass you need to use the black and white newspapers.
In a couple of weeks you can add more shrubs to your garden in you wish, but don't turn the whole area up, just dig your hole you need. The newspaper will still be doing its job of killing grass and breaking down.
If you are starting a brand new bed, you can use this method or you can rent a sod remover. Sod removers are quick and easy as well, once you get the hang of the machine. But if you have grass between shrubs and trees, and you are constantly breaking branches trying to force the lawn mower in between these areas, then consider killing grass with newspaper and mulch.
This protects the root area, and helps to feed the ground. The mulch helps to nourish the ground and keep in moisture and keep down weeds.
I had a front yard that was like a checker board for a tree here and a shrub there, and I would have to weave around them each year with the lawn mower. But finally they just started getting too close to use the lawn mower, and liked the idea of forming garden beds with these shrubs and trees. It would save on lawn cutting!
I edged the area first, so that I had a area that actually divided the garden bed from the actual lawn. Killing grass with newspapers is a great way to preserve the roots of plants and actually feed them in a nice mulched garden. Give it a try.