The supplement has 10% calcium, and the layer feed has 4% calcium.
Is this ok to give to chickens than are not laying, including the rooster?
Check the calcium on the feed you are already giving.
The amount of calcium they will be getting will be based on weight of that feed, and the supplement feed.
Roosters and non-laying birds should be receiving about 2% calcium, so sounds as if they're already getting a super-whammy on that.
https://www.backyardchickens.com/threads/what-of-calcium-for-roosters.1223017/
But... for future reference; when mixing feed, you can determine what the new percentages will be by weighing out the portions...
Let's say that 'Feed A' has 4% calcium
and that 'Feed B' has 10%
Now let's say that you will be using 9 parts of 'Feed A' and 1 part of 'Feed B' (by weight, not by volume).
Multiply the number of parts of each feed by the percentage of the nutrient (in this case, calcium), adding those figures together, then dividing the sum by the total number of parts.
9 parts 'Feed A' by 4 (percent) PLUS 1 part 'Feed B' by 10 (percent) = 36 PLUS 10 = 46. Divide this number, 46, by the number of parts... in this example 10 parts... to find out that it would increase the calcium in the feed to 4.6%.
Given that your flock is already receiving a lot of calcium, I wouldn't add that supplement to your flock's feed, opting for a lower calcium feed to mix with, instead.