After reading over everyone's responses, and seeing your own, here's my stance on it:
Has any of the advice they've given actually helped?
Has any of these beta readers explain why they don't like your work or clarified to you what is lacking? Have you been able to improve in your work?
If the answer is yes -- make sure you keep that reader. It's good to have someone who can catch some errors in your work. We all need constructive criticism.
However, if these readers have not bothered to explain or clarify and just give you blatant"oh, this will never work", this is where I disagree with a good number of replies that said to still "keep them".
When it comes to a negative comment and constructive criticism, there is a fine line between someone "trying to help" and someone" trying to tear you down". In a lot of cases, people cannot tell the difference between the two. So someone can think they're helping. But if all they give is negativity without:
A) Explaining why they felt that way
B) How you can improve
Then they're not really helping.
The same goes with "good feedback". If they're not explaining why and all they say is "wow, this is awesome!" -- they're not helping.
They're beta readers -- they have to be able to explain why things just didn't click or did click for them. It's a two way street, and you have to deliver just as much as they have to give feedback. But you can only deliver if you have good, concise, STRONG feedback.
One way to pick up on good feedback is as follow:
They may or may not provide both cool and warm feedback. The former is when they tell you exactly what can be improved and why they feel that way. The latter is when they tell you where you went right and maybe how you can lead with that idea. Unless you're just completely new to something, you should at least have one thing good going so far.
They will give "Why and How". The Why tells you why it did or didn't click for them. The How is how you can improve your work. Clarification and Elaboration are needed, always, if you're trying to give criticism. Thing like "this is so cliche, like wow" or "this is hot garage" are not good examples because they didn't explain anything. What's a cliche? Can they point it out? Why is it hot garbage? How can I do better? If they can't answer those questions, they're not really being helpful.
In the end, it's up to you to either ignore some feedback or take some in. I say it's better to look closer at feedback where the person took time to explain themselves and their perspective. At least then, you know someone took time to read over your work and try to see where you were going. It's also good to have readers with some experience (writing, drawing, story-telling, whatever).
But remember -- there is a difference between people who try to help and people who try to tear you down. And there is a difference between someone helping and someone trying to fluff you up.
And it's up to you to know that difference and improve from there.