1. Shedding blades
This is probably the most common way to get rid of the winter coat. The handled metal loop (there are other types, but the loop is very common) that is the shedding blade has small teeth that pull out loose hairs that the horse is shedding. A shedding blade is easy to use and is a tool any rider should keep in their grooming kit as the warm weather approaches. It is also very efficient at removing dried mud from a horse's coat in the spring. Just take caution when using this tool around bony areas of your horse's body, such as the legs or the withers. It is not recommended to use a shedding blade on these areas because of how rigid it is.
2. Hot baths
Bathing your horse with hot water essentially speeds up the shedding process: instead of waiting for the weather to come to finish the shedding, the hot baths trick the horse's body into thinking it's hot out. Giving your horse a series of hot baths the continue to encourage more rapid shedding. Take caution on the time of day that you give your horse the bath: you wouldn't want him to catch the chills, would you?
This option is truly situational. If a horse hasn't been groomed at all throughout the winter, it's coat is most likely very thick, fuzzy, and way out of control. Now that spring is here and you would like to start working the horse again, clipping may be a huge timesaver. It can save you many hours of grooming and bathing. Check the weather forecast before clipping: you don't want your horse bring snowed on right after being clipped.