The FCC Commissioner is appointed, per 47 USC 154, by POTUS, subject to approval by the US Senate (as a member of the Commission). Thereafter he serves for 5 years. However Article 2 of the Constitution allows removal from office:

The President, Vice President, and all civil Officers of the United States shall be removed from Office on Impeachment for, and conviction of, Treason, Bribery, or other High Crimes and Misdemeanors.

Does Ajit Pai own any stock in any ISP or phone company. Well upon investigation, yes, yes he does. He has between $250,000 - $500,000 in Vanguard 500 Index Fun, Admiral Shares. This investment fund has approximately 25.6% of the money invested in Information Technology, but that is pretty broad, but what is more interesting is 1.9% of that fund is invested in Telecommunication Services. So this means he has between $3225 - $6450 invested in telecommunications companies. How is this legal?

By revoking Net Neutrality, this allows telecommunication companies to make more money and creates a conflict of interest. So why in the heck isn't Congress doing anything about this?