To put it simply, sell when you are profitable or you have a target price you want to achieve. There is no limit to what price you have to sell your BTC.
You can sell it and buy it again if the price starts to fall.
Selling to secure your capital is also workable and it is a few safe ways.

Just wait some days to cut a good profit from it. It is really not time for selling Bitcoin. It has already crossed $60k and hopefully within short possible of time, it will reach $100k. So hold Bitcoin and wait some more days if you want to get good profit.

I suggest you sell half and wait for pumping or dumping. If you sell today half it’s best price for you. You can rest after sell.

Bitcoin struggled past the $ 61k resistance price, several times trying to get past the $ 61k price tag but always failed.  There may be a correction
to the support price at $ 57k. So now is the right time to sell Bitcoin. But don't sell all the Bitcoin we have, just in case the Bitcoin price manages
to rise above $ 61k. We still have to monitor Bitcoin's current movement, because there are many possibilities that could happen. If you want to
buy altcoins, you should buy BNB, because the performance for the past few days is quite good and the price might go back up to ATH price.

Selling BTC is a matter of comfort and it varies per individual.  There isn't any such time to sell. You sell when you have a reason to and not just because you felt you've made profit. The reason for a sale could be very possibly that you've made profit but, is it the best?
Well, selling with the idea of buying when it falls is a good idea but, its only good as much as you know or is able to determine whe  the market has actually hit a low.

But importantly,  bitcoin is not a currency you just sell. It appreciates with time so, its best to be patient with it. But, the issue of selling is always up to you to find the best time that suits your own purpose or need as at that time.

it is okay to sell bitcoin these days. but I suggest selling 30% of your total assets, because I think you can use your other assets to be used to get bigger profits.

I agree with your way of thinking but if bitcoin is held because of the results in 2018 not because buying when it starts to increase, of course it will be different again. reasonable because it has made a profit so that it can be sold with the best possible purpose for what you will do.

now we know bitcoin continues to increase so it would be a shame if you have to sell all of it because the increase is still ongoing and we don't know how long, but it is estimated that until the end of the year it can be concluded how much bitcoin will be worth, of course you will lose if everything is released at this time.

I am not longer holding bitcoin and always take short term to buy or sell bitcoin, if have chance for selling bitcoin on higher price like yesterday I will sell my bitcoin, but keep buy back when bitcoin going down. I think is better every time my earning increase and I could use for another investment and could get profit again, if keep holding on bitcoin only maybe I have been more patient waiting when bitcoin really touch higher price.

If you feel that you have lost an asset because you have sold at the lowest price and bought at a high price, my advice is to do Cutloss to minimize losses.
I think the current price hasn't reached its highest value yet, there are still other high prices. For that, always use the long-term method by putting some of the assets you have.