No, you must not screen participants out of your survey based on criteria which is not specified using Prolific's prescreening options.
By this, we mean that the full eligibility criteria for your study must be applied to your prescreening, so that all participants who are sent to your study can complete it and receive the reward. You cannot simply reject participants if they do not meet the criteria you're looking for, or exit them from your survey, if the criteria wasn't applied to your prescreening (see step 4 here).
It is very frustrating for participants to get unexpectedly kicked out of studies, and our platform has been designed to help you recruit only the specific sample that you require for your study.
If you want to recruit a niche demographic that you can't obtain using our existing prescreening filters, you should contact our support team to request the creation of a new custom screener: https://helpcentre.prolific.ac/hc/en-gb/articles/360009093774-Can-you-create-a-new-prescreening-filter-for-me-
For example, I'm a researcher who only wants to recruit individuals whose favourite flavour of ice cream is chocolate. However, I could not simply publish my study, ask the question in my survey, and reject any participants who respond that their favourite flavour is vanilla or strawberry (or exit them from the survey).
As there is no existing screener related to participants' favourite ice cream flavours, I would instead have to contact Prolific and request the addition of the following screener:
"What is your favourite flavour of ice cream? Vanilla, Chocolate, Strawberry...etc."
I could then apply this custom filter to my study's prescreening, with only the 'Chocolate' response option selected. This way, only participants who responded that their favourite ice cream flavour was chocolate in advance of being sent to my study would be eligible to take part.