Termination when only one partner remains

The partnership form also ceases to exist if a transfer of partnership interests occurs and only one partner remains. For example, a partnership terminates when a 60% partner acquires the interests of two other partners who each have a 20% interest in the partnership (Regs. Sec. 1.708-1(b)(1)). The partnership is terminated as of the sale date of the partnership interests.

See link: https://www.thetaxadviser.com/issues/2019/oct/partnership-terminations-change-form.html