How remove wireless package in mikrotik rb750gr3 and after update 7.13.1 version client complain internet to slow

You should know since you added it there (at least someone did) ... it doesn't appear on it's own on Hex.

Under System Packages, select wireless, then button uninstall and next reboot device.
ATTENTION: if that Hex device is used as capsman manager for legacy wifi devices, it IS needed !!

You should know since you added it there (at least someone did) ... it doesn't appear on it's own on Hex.

Are you sure? Maybe the ROS "migration logic" on upgrading to 7.13 installed it.

You should know since you added it there (at least someone did) ... it doesn't appear on it's own on Hex.

Actually it is added automatically, when installing 7.13.x.

And indeed required for making the old CAPsMAN available. SO, unless running (old) CAPsMAN, it can be uninstalled:
https://help.mikrotik.com/docs/display/ROS/Packages

Actually it is added automatically, when installing 7.13.x.

Not if it wasn't already there (which can't be pre-7.13).
On non-wifi devices, to my knowledge, wireless is not added automatically when moving to 7.13.

There was no "wireless" package < 7.13. But "CAPsMAN" was part of any RouterOS bundle - right? MT extracted (legacy) "Wireless" and (legacy) "CAPsMAN" into a new package called "wireless". Regardless if the device has wireless hardware or not. The fact, that MT made one single "wireless" package instead of splitting properly into 2 packages: "wireless" and "legacy-capsman". So people depending on legacy CAPsMAN can simply install a capsman package - instead of installing the whole wireless-driver stuff which is then unneeded again. MT developer decisions.

click on the settings icon next to package and set to uninstall.
then reboot router.

Not a native English speaker myself, but it seems to me like the core explanation is clear as mud:

RouterOS packages

Starting from RouterOS 7.13, the routeros (system) package and one of the wireless packages are needed for the basic operation of a simple home router.

802.11ax WiFi APs require radio drivers, which are provided by the wifi-qcom package or (for RouterOS version before 7.13) the wifiwave2 package.

Previous generation WiFi APs require a wireless package.

Other packages are optional and not required for a home router. Install them only if you are sure of their purpose.

Two kinds of devices, "simple home routers" and "Wi-Fi APs", these latter ones clearly divided in "802.11ax", if on 7.13, not to be confused with "previous generation".

The only missing part is that you shouldn't upgrade on wednesday nights (if there is a full moon, but not if the wind is blowing from south, then you can upgrade but only before 3:00 AM, obviously this applies only to previous generation devices, unless they are ARM, but if they are ARM64 it is fine).

Which part is not clear? If you have a question, I can answer

Which part is not clear? If you have a question, I can answer

I am only having a bit of fun, but if we want to talk seriously, every single sentence in the quoted snippet is either wrong or confusing, or both.

What is a "simple home router"?
What is considered "basic operation"?

Let's say that a rb750gr3 installed in a home is a "simple home router".
It has no Wi-Fi, so there is no need for that added package, unless it is used as a Capsman controller, which is probably not "basic operation".

My Hex still was on 7.12rc5.
So did upgrade to 7.13.1

No wireless package. It does not come by itself.