There are a number of reasons that a gardener might want to get rid of flower bulbs. They may have spread out of the area in which they were intended to grow; they might be left over from a previous tenant; or they may simply no longer fit into the garden design. Whatever the case, flower bulbs can be extremely persistent, and killing them completely can take both time and multiple attempts.
Dig out the bulbs. Larger plants can be pulled from above ground, but this may leave sections of the rhizome, or bulblets, behind underground. Any matter left below ground will send up a new plant the next spring. The most effective way to dig out bulbs is using a hand trowel. Dig up an area that is at least 6 inches wider than the apparent bulb bed, and at least as deep as the largest bulbs.
Mow over the flowering bulbs, or cut them down with a weed eater. This will not only prevent the plant from seeding, but will also open the pores so that spraying an herbicide is more effective.
Apply a general herbicide, like glyphosate, 2,4-D, or imazaquin. These products are generally nonselective and are effective at eliminating unwanted flowering bulbs. However they should not be used in areas where they might damage other nearby flowers, ornamental trees, shrubs, turf, or herbs. The herbicide should be applied the first time in November, and again in the following spring.
Dig any remaining bulbs out with a trowel the following spring. Bulbs can be extremely persistent, so digging and spraying may have to be repeated as many as three growing seasons to completely kill the bulbs.
When digging out bulbs, make sure you dispose of them in an area where they cannot grow. Bulbs can be discarded in a gravel road or driveway or burnt to insure that they are killed. They can also be stored in a burlap sack in a cool dry place and replanted in a new location the following spring.