I'm quite hesitating to do that, since it tells you that "If you disable a built-in app, other apps may misbehave". What do you think?
Also, I changed my mind I don't want to root it with KingRoot, since some people found out that there's a malware with it. Can you teach me how to root? Not using any kind of rooter like the KingRoot.
Keep in mind that rooting might not be a complete fix for all your issues. Once rooted you also take on a greater role in the general maintenance and upkeep of your tablet. Be very judicious about doing things like side-loading APKs, you're still better off sticking with apps from the Play Store. One 'nice' thing is since your carrier most likely won't be supporting your tablet model any more, you won't have to worry about OTA updates (OTA updates and rooted devices are generally not a good mix). Also, as you stated you want to clean out some of the built-in apps and optimize your tablet, with root privileges it's very easy for some to get over-zealous and remove apps and services that are actually necessary for your table to function. (You're much better off disabling items first, waiting to see if everything is still working OK, and then removing them later if necessary.)
As for one-click rooting apps like KingRoot, they are indeed an issue. They often do things like mess with your browser homepage, alter default search engines, and typically link themselves to anonymous servers overseas. That's how they pay their bills, they monetize their services. It's not an all-bad situation though, for a lot of mobile device models there is no viable option to root, plus once you're rooted locking down and securing your device is much easier (i.e. if say, Kingo, is connecting to its home office you can just block its online connectivity so none of your personal data can be shared.)
But again, rooting won't be a magic cure for any ills, it will be a matter of you also take on the responsibility to research those alleged 'cures' before you actually perform them. So just think about why you want or need to root your tablet. I'm tentatively suggesting you might want to try to manually root your tablet - here's a link from XDA Developers, a generally respected Android site, to read through (carefully):
https://forum.xda-developers.com/showthread.php?t=2684210
By tentatively, I am hesitant. Rooting any device using whatever method can be risky and there is a likely chance if something goes wrong that the device gets bricked. With a lot of mobile devices, if a factory stock ROM is available so there's often a 'back door' escape where to rescue a bricked device, re-flashing the stock ROM will restore it to working condition again. Doing I quick search I wasn't having much luck finding if a stock ROM is available for your model of tablet, contacting HP directly to see if it's available might be the prudent thing to do if you do opt to root your tablet.