There are two separate endings: finishing a test, and finishing the whole assessment. It is worth knowing which one you are looking at.
Finishing a test
A test ends when you submit it, or when time runs out on a timed one.
Your answers were already saved as you gave them, so submitting is confirming you are done rather than sending your work for the first time. See how your answers are saved.
If time runs out before you submit, the test still ends properly. The answers that reached us before the deadline count, and anything left blank stays blank.
Going back to a test you have finished
You cannot. Once a test is submitted or its time has run out, it is done.
This is worth knowing before you submit rather than after: if you have time left and flagged questions outstanding, use the time.
Finishing the assessment
When every test is complete you reach a completion screen confirming all tests completed and answers submitted. That is the point at which your assessment is genuinely finished and with the employer.
Until you see that screen, something is still outstanding. If you think you have done everything but have not seen it, go back to your assessment list and check for a test you have not started.
What happens next
Your results go to the employer who invited you. They decide what happens next, and they contact you.
We do not tell you how you did, and we do not know the employer's timescale. See what happens to your results and do you get to see your results?.
Can you close the window now?
Yes. Everything is submitted and there is nothing left running. If you want to keep a record, the completion screen is the thing worth a screenshot: it is your evidence that you finished, and when.