Apply an herbicide. Herbicides are either selective or nonselective. Selective herbicides kill only a particular wild grass, whereas a nonselective herbicide kills everything it touches. Thus, you need to determine which type of wild grass is growing in your landscape and apply the appropriate herbicide.
Apply a natural herbicide. If you are not comfortable applying an herbicide over your landscape (perhaps you have pets), consider a natural alternative. Distilled vinegar, urine and corn gluten will all kill wild grass. Of course, these natural remedies will kill nonwild grass as well.
Use a rototiller to till your landscape. A rototiller is a landscaping tool that is designed to turn over soil. The consequence of this is that the roots of the wild grass (along with the roots of plants and trees) are destroyed. Once you have used the rototiller over your landscape, you are free to start from scratch.
Install edging fabric around your landscape. Edging fabric, available at most home and garden stores, is essentially a miniature fence that prevents wild grass from invading your landscape. Of course, edging fabric is useless against wild grass that has already invaded your landscape.
Get some animals. This is not a realistic option for everyone, but if you are open to it and it is feasible, goats, sheep and cattle will be happy to control your wild grass problem.