I've got myself in a right mess with my postgres migrations. Is there a way (other than removing and redeploying the whole stack) of resetting the migrations so I can start again?

You can reset your migrations inside the SST console, just click on the first migration you have made and it will reset all the rest

Mine's completely corrupted, I've misunderstood how it all works and need to start again.

Then simply renaming your cluster and deleting the previous one should work

Thanks, will try that in a bit.

You can truncate the kysely_migrations table