A piano is a musical instrument, so it comes under the heading of the texts which forbid musical instruments and forbid listening to them. The evidence for that has been explained in the answer to question no. 5000 and 96219.
Whatever is proven to be haraam, it is not permissible to sell it, rent it, carry it or help with it in any way, because that is helping in sin, and Allaah says (interpretation of the meaning):
“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”
The accountable Muslim is enjoined to denounce this evil, so how can he keep quiet about it and carry it or help to keep it? Allaah says (interpretation of the meaning):
“Those among the Children of Israel who disbelieved were cursed by the tongue of Dawood (David) and ‘Eesa (Jesus), son of Maryam (Mary). That was because they disobeyed (Allaah and the Messengers) and were ever transgressing beyond bounds.
79. They used not to forbid one another from Al-Munkar (wrong, evildoing, sins, polytheism, disbelief) which they committed. Vile indeed was what they used to do”
The curse befell them because they failed to denounce evil.
Al-Nawawi (may Allaah have mercy on him) said in Rawdat al-Taalibeen (5/194): It is not permissible to be employed to move alcohol from one house to another, or for anything else that is forbidden such as playing instruments and wailing. Just as it is haraam to accept payment for these things it is also haraam to give it. End quote.
Based on this, working for a piano removal company is haraam, because it involves helping in sin and approving of evil.
If a person is employed to move household goods and finds musical instruments among them – apart from the daff – it is not permissible for him to move them, for the reason given above, which is that carrying them and moving them is helping in sin and approving of evil. Even though it seems difficult to refuse to move these instruments, the consequences will be good, if Allaah wills, because if a person gives up something for the sake of Allaah, Allaah will compensate him with something better than it, and the one who prefers the reward of the Hereafter over worldly gains, will inevitably attain worldly gains (from halaal sources). This attitude of his may be the cause of the kaafir’s being guided and wanting to find out about this great religion which makes its followers give up money to seek the pleasure of Allaah.
We ask Allaah to guide us and you and to make us and you steadfast.
And Allaah knows best.