If a creature is declared as a blocker and then is removed before damage, does the attacking creature become unblocked?

When a creature is declared as a blocker during the Declare Blockers Step, the attacking creature's status immediately changes to 'blocked' (CR 509.1h). This status is locked in at that moment and does not change if the blocking creature later leaves the battlefield or is otherwise removed before the Damage Step.

CR 509.1h states explicitly: 'Each chosen creature still controlled by the defending player becomes a blocking creature. Each blocked creature becomes a blocked creature.' The blocked/unblocked status is set during blocker declaration and is not revisited simply because the blocker disappears.

This means that if the attacking creature has no special abilities like trample, it will deal its combat damage to nothing — it cannot be redirected to the defending player just because the blocker is gone. The attacker is still considered 'blocked' for the entire combat (CR 509.1h, 700.4).

Example: You attack with a 3/3 creature. Your opponent blocks with a 1/1 token. You then cast Lightning Bolt targeting the 1/1 token, destroying it. Your 3/3 is still a 'blocked' creature and deals its 3 damage to nothing — your opponent does not take 3 damage.

The only exception is if the attacking creature has trample (CR 702.19). A trampling blocked creature can assign excess damage to the defending player, but since there are now zero blockers to assign damage to, all 3 damage would trample over. So trample does matter here — but the creature is still technically 'blocked,' just dealing trample damage through.