Spells often leave some sort of residue behind. This can include candle stubs, incense ash, bits of paper, dried petals, and so on. Most of the time, that gets cleaned up during or after an individual spell. However, sometimes magic happens in haste and not everything gets picked up. Here is a ceremony for clearing away the remnants of old spells.
First take everything off your altar. Empty and wash the incense burner. Empty and clean the candleholders. Polish the athame. Wash the ritual bowls, chalice, and stone or pentacle. Painted icons or other delicate items can simply be dusted. Clean the top of your altar with furniture polish (if wood) or glass cleaner (if glass). Make sure you have a fresh supply of incense, charcoal, candles, and other consumables. Check that the matchbox or lighter is full.
Now place the cleaned altar tools back in their customary positions. Say:
All that has gone before is over