A termination ends the employment relationship, whether for performance, conduct, or because the role is no longer needed.
At-will is not unlimited
Most employment is at-will, meaning either side may end it without cause. That does not permit ending it for a prohibited reason — discrimination, retaliation for a protected complaint, or in breach of a contract or policy the business itself set.
The practical consequence is that a business rarely has to prove cause, but frequently has to show the reason was not a prohibited one. That is what documentation is for — see employment practices liability.
What should exist beforehand
For performance, a record of expectations set and shortfalls addressed — see performance management.
For conduct, a record of what happened and what was established.
A termination that is the first written record of any problem is the hardest to defend, regardless of how justified it was.
Consistency
Treating similar situations differently is one of the strongest arguments an employee can make. Two people with comparable conduct and different outcomes needs a documented reason for the difference.
Doing it
Brief, in person, with a witness where possible. The decision is communicated rather than debated; the conversation is not the point at which it is reconsidered.
Property recovered: keys, vehicles, tools, devices. Access to systems and accounts removed the same day.
Obligations that survive
Final pay is due on a timescale set by state law, sometimes immediately, and the deadlines are short.
Accrued leave may have to be paid out depending on the jurisdiction and the policy — see paid time off.
Records must be kept for a period after employment ends — see record retention.
Benefits continuation notices may be required.
Get advice first
The specifics are state law and the deadlines are unforgiving. A conversation with an employment attorney before the termination costs a fraction of one afterwards.