Leave the flowers on because that's where the fruit will grow. Height of your tomato plants depends on whether you have determinate or indeterminate plants. Either way, never remove flowers. On indeterminate plants (or cordon varieties, not bushy varieties), you can pinch out the shoots which grow from the main stem, next to a leaf.

Of course leave the blossoms on. That's where the tomatoes come from.

I'm assuming that that is 8-10 inches. 8-10 cm would be a sign of extreme nitrogen deficiency, or way too small containers. Both would make it difficult to ripen good fruit.
8-10 inches is consistent with most of the shorter determinate varieties, which are often sold as "bush" tomatoes.

Thank you all for the answers, as I could not get out to buy plants I dried some tomatoes and planted the seeds I do not know what type they are but I am very hopeful.

I'm growing Rutgers Tomatoes which is also a very tasty determinate. The first couple blossoms were duds, but now it's starting to produce. Amazing how quickly the plant grows especially when the days heat up.

Unless they are labelled "Heirloom", most tomatoes from the store are hybrids. That's not a bad thing in itself, but the seedlings are likely to be of all sorts--different colors, sizes, flavors, shapes, etc. You never know...you may wind up with the best tomato plant of your life!

Heirlooms are awesome, but they are very susceptible to blight and everything else that could go wrong.

I can not wait for them to grow now, its my first time challenge I normally take the easy road and buy the plants all done for me. thank you