As we can't perform a cooperative close yet, once your channel is closed, there is a grace period of settleTimeout blocks during which the counterpart can claim a higher signed balance proof sent by you. Only the tokens you transferred can be claimed by your partner. After settleTimeout blocks, your channel's state automatically becomes settleable, which is like closed but when settle can be called:

await raiden.settleChannel('0xtoken', '0xpartner')
# resolves to settle transaction hash, after it is mined

## channels$ output:
# Raiden channels: {
#   '0xtoken': {}
# }

Once channel is settled, it's gone from mapping, and you can open the channel again, if desired.