So lets start with a very simple technique-
1-First of all you have to open this - Truecaller Unlist
2-Now you have to enter your valid mobile number which you want to hide with a country code.
3-Fill the form completely with all correct details.
4-Click on the Unlist option.
Note- If you have registered your number with Truecaller then open the Settings option in application of Truecaller, select About Tab and click on Deactivate.
Congratulations, now your personal data will not be shown to anyone.