You can’t extend or change status from ESTA while in the U.S. If you want to pursue a business opportunity legally, you’ll need to leave the country before your 90-day stay expires and apply for an appropriate visa, like a B-1 or E-2, from Romania.

Romania is part of the E-2 treaty country list, which means you may be eligible for an E-2 investor visa if you invest in and manage a U.S. business. This visa must be applied for at a U.S. consulate abroad, not while you're on ESTA.

Overstaying your ESTA, even with good intentions, can trigger future travel bans or visa denials. It’s better to return home and apply properly than risk violating your current status and harming your long-term immigration options.