"mich" wrote
| It is not mine. It was just left by its owner. I
| did contact the owner about it but never got a reply.
| That was five years ago.
| Are you still in contact with the owner? If you are, it
| would be prudent to send a letter recorded delivery telling
| him you intend to dispose of the piano in, say, 28 days
| from the date of the letter.
| I am not in contact with the owner. ... hence I have no knowledge
| of her current wherabouts.

Nonetheless, a recorded delivery letter to this woman's last known address
would be a prudent move. It should be returned by the PO as 'not known'.
Keep it safe, and if the woman does turn up claiming her piano and
threatening lawsuits you can use the returned letter as evidence that you
did take reasonable steps to locate her before considering her property
abandoned.

Owain