retire - leave one's job and cease to work, typically on reaching the normal age for leaving service.
to run (a business, a company) - to operate, to direct, to oversee, to manage, to lead a business, a company,  organization.
set up - establish a business, institution, or other organization. It means starting up a business, company.
to be redundant - no longer employed because there is no more work available. Literally it means no longer needed or useful; superfluous.
to be sacked - being fired  from a job, usually because they have done something wrong or badly, or sometimes as a way of saving the cost of employing them:
work shifts - Shift work is a work schedule that is performed in rotations. Different groups of workers often do the same jobs in rotation. Basically it's work in turns. Workers work in turn according to their schedule.
to quit - to wilingly give up or resign one's job or position. 
freelance - an individual who makes money on a per-job basis is a freelancer. They usually earn on a per-task basis and generally work for a short time. In simpler terms, they do not work for a firm.

self-employed - A self-employed person does not work for a specific employer who pays them a consistent salary or wage. Self-employed individuals, or independent contractors, earn income by contracting with a trade or business directly.

part-time job - 
temporary job
unemployed