It's a fly (Diptera), in the family Sciaridae.
These like to lay their eggs in damp compost. If you've removed the plants that should stop you getting them inside.
If you want to help get rid of them from the plants you removed then changing the compost will help. Keeping the plants a little drier will likely stop them from wanting to lay eggs in your pots.
There will always be more Sciarids, prevention is the best way. Use a soil based compost as the peat based ones are more likely to attract them due to poor drainage.
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