To cure vampirism in Skyrim, the method depends on the stage of the disease you have:

Early Stage Vampirism (Sanguinare Vampiris)

• If you have just contracted the disease and it has been less than three in-game days, you can cure it easily by:
  • Using a Potion of Cure Disease.
  • Praying at any shrine.
  • Consulting a Vigilant of Stendarr if you encounter one.
    These methods will remove the disease before it fully develops into vampirism

Full Vampirism

• After three in-game days, if you have become a full vampire, curing it requires a more involved process:
  1. Travel to Morthal and find Falion, a wizard who specializes in curing vampirism. He can usually be found outside the town at night or inside during the day.
  2. Speak to Falion and start the quest "Rising at Dawn" by discussing vampirism with him.
  3. Obtain a filled Black Soul Gem. You can buy an empty Black Soul Gem from Falion or Enthir at the College of Winterhold, then fill it by casting the Soul Trap spell on a humanoid enemy and killing them while the spell is active.
  4. Return to Falion with the filled Black Soul Gem. He will lead you to a summoning circle near Morthal at dawn.
  5. Stand in the summoning circle while Falion performs the curing ritual, which will remove your vampirism.
• Note: If you are "blood starved" (haven't fed recently), Falion may attack you, so you need to feed on a sleeping NPC to remove this state before the ritual

Alternative Cure

• You can also cure vampirism by becoming a werewolf. Joining the Companions and contracting lycanthropy will instantly cure vampirism and grant immunity to the disease while you remain a werewolf

This process can be repeated if you become a vampire again later. The main cost is acquiring and filling a Black Soul Gem each time you want to cure vampirism