This article applies as of PRTG 21

A Sensor Indicates a Device's Current Status

A sensor always shows the current status of a device for the aspect it is monitoring. For example, if a device is not reachable, the PRTG Ping sensor on this device will change to the error state to show the down status. You cannot change this, because otherwise the sensor would show incorrect information.

You can, however, disable all notification triggers for a sensor. If you do and a device is down, the according sensor will show the error status, but you will not get any notifications.

How to disable all notification triggers for a sensor

• Right-click on a sensor, go to Edit and then to the Notification Triggers... tab.
• Uncheck the Inherit all triggers from parent objects and use the triggers defined above option.
• Check the Only use the triggers defined above option.
• Make sure that in the Notification triggers section above, you select (no triggers defined) in the dropdown list.

More

See the manual section Notifications for more details.

Custom Ping Sensor PingWarning suites the need but it's another problem rised: depended SNMP sensors for this device now going to error state :-(

So question: is it possible to set paused state for SNMP sensor in depend of WARNING state of another sensor?

no, sorry a sensor in warning state does not trigger dependency

So How to create a ping monitor that monitors an IP ? Maybe a simple question, but in PRTG, how or where can I fill in the IP number.....

The IP address is set at the Device level, not at the sensor level. You need to create a Device first, enter the IP address of that target device and then create a sensor on the device, it will ping that IP.