There are valuable elements in the wiring of phone chargers which are important to recover and recycle. See e-waste
Keep your old phone chargers as backups to leave at work, or to take when travelling.
There are components in phone chargers which can be recycled. See cellphone to read about the RE:MOBILE recycling/product stewardship programme.
The Whanganui Resource Recovery Centre recycles e-waste (fees may apply).
Please keep from landfill wherever possible.