I need to disable the keyboard to press the button behind
You can use Activities - Execute Command
Command: mobile:hideKeyboard
Parameters: new Dictionary<string, object>() {} C# syntax
In order to get a list of all the supported functions just execute this activity with a random mobile:unexistentfunction and you should get back a list with all the supported functions. To find out more about these you can go to Command Reference - Appium XCUITest Driver
Note that these commands are driver specific!