Bicycles that are in good condition can be donated to local charities by using a reuse container at some Household Recycling Centres. Damaged bicycles can be repaired locally too. They may be suitable for reuse through a local reuse network such as Freecycle or Freegle. There are now a large number of reuse groups on Facebook.
Otherwise, damaged bicycles can be taken to a local Household Recycling Centre and included in the scrap metal or waste to landfill container depending what the bicycle is made from.