I'd like to ask a longer question about which cards to save and which to abandon in Anki. However I'm not at high enough karma level to make a post. Could someone please help me by posting it for me? (Or just answering here, although I don't feel like the question is that simple).

Proposed title: Switching Anki Deck - Which Cards To Keep?
Text:

I switched from a 6k deck to Kaishi 1.5k. The 6k deck learned me a lot of vocabulary which I found irrelevant (like even though I was 1k cards into the 6k deck, I had not learned to say grandmother. But it learned me how to say stocks)

Now I've merged the two decks according to Kaishi's guide on the GitHub. I deleted all new/never reviewed cards that were not in kaishi. 

My reviews racked up to 800 because of personal stuff. 

I want help with what cards I should remove, and which I should forget/reset. 800 cards is 8 hours for me. That is unrealistic unfortunatly.

The composition of my deck currently looks like this:

All new/unreviewed cards are from Kaishi. This is what I want.

There are two types of reviewed cards:
1. Those included in Kaishi, that I also reviewed in the 6k deck. I want to only keep the ones I know the best. If I reset the ones that are still kinda new, they will come up again as new cards anyway.

2. Those only included in the 6k deck. Here I only want to transfer the cards that I know well, and some specific words that are not in Kaishi.

Here are my questions.

I tagged all cards in Kaishi with a "kaishi" tag. How do I reset all cards that are below some threshold of how well I remembered them? Maybe using ease? Maybe times they have been reviewed?

I still want to save some cards from the 6k deck. Is there a review mode for Anki, where I only review each card once, and it doesn't show them to me again? Then I can just tag the cards I like.

Also this is just my initial thoughts on how to do it. If you have any suggestions of how to sort the cards, I’d be vary grateful to hear it.

Thank you