How can I return to iOS9 (from updated iOS 10)?

You can't. There is no supported way to downgrade iOS versions, and no guarantee this would cure your issues even if it were possible.

Your best bet is to perform normal troubleshooting steps:

TroubleShooting Steps

1. A Reset may cure some bugs. Hold down the Home and sleep/power buttons until the apple logo shows up.

   If still not resolved:

2. Reste al Settings. Go to Settings->General->Reset->Reset All Settings

   If its still not resolved:

3. Restore the device as new.

Use iTunes on your Mac or PC to restore your iPhone, iPad, or iPod to factory settings - Apple Support

You need to first download the IPSW file. Then you need to put your device in recovery mode. Then you need to restore your device.

This is not easy, and Apple will stop signing the code without warning. If you do not have an archived backup of you device from before iOS 10, you will have to start from scratch.

All that said, I am having no issues with iOS 10. What issues are you experiencing?

MrNo1175 wrote:

Well, applications can't access camera and microphone,

Make sure the Applications are allowed to access camera and microphone in: Settings->Privacy->Camera, and Settings->Privacy->Microphone by making sure the relevant applications are turned on there.

MrNo1175 wrote:

iTunes can't connect with iPad

Make sure the iTunes version on your computer is iTunes 12.5.1 As it is required for devices running iOS 10.

MrNo1175 wrote:

I can't delete any application by pressing X button...

Make sure Deleting Applications is not restricted in Settings->General->Restrictions->Deleting Apps.

i want ios9