Good pianoforte instruments have a long life if looked after and placed in the correct location. Should disposal of an instrument be necessary, directly speaking to the local refuse centre of your community is usually the first step. There, you will gain information on how best to dispose of your instrument.
An alternative is to ask your local specialist dealer who is used to disposing of old instruments and can be helpful with advice. Please be aware that often, reconstruction of very old instruments is not effective.
Uprights and grand pianos with electric/electronic fittings (for example muted piano or self playing pianos) must have their electric/electronic components removed and disposed according to the regional and legal rules. Please ask your local authorithies.