Minecraft Java Edition Commands – How To Use /fill Command

Try: /execute <selector> ~ ~ ~ fill <relative coordinates> air 0 replace wool

[EDIT]

If you are wanting the block to disappear after a certain amount of time, say, 30 redstone ticks (60 game ticks), you could summon a WitherSkull below the player and use the execute command on it.

To make the block disappear, you would add a new scoreboard command, lifetime, for instance, and run /scoreboard players add @e[type=WitherSkull] lifetime 1 with a setblock or fill clock, then execute another fill command on every wither skull with a certain lifetime value, like:

/execute @e[type=WitherSkull,score_lifetime_min=31] ~ ~ ~ /fill ~ ~ ~ ~ ~ ~ wool 0 replace air.

Then, you would kill the wither skull: /kill @e[type=WitherSkull,score_lifetime_min=35].

Here is a screenshot of what I did:

For black wool:

/fill X1 Y1 Z1 X2 Y2 Z2 wool 15

The value after the block type is its data value, which is 15 for back wool.

For oak planks

/fill X1 Y1 Z1 X2 Y2 Z2 planks