From RC desktop phone app you can set your outgoing caller id to blocked from settings--> Calls--> Outgoing --> Outbound Caller Id--> blocked

From online portal ref: https://support.ringcentral.com/article/3614.html#:~:text=Go%20to%20Settings%20%3E%20Outbound%20Calls,to%20access%20your%20extension%20settings.&text=Alternate%20Caller%20ID%20%2D%20used%20if,of%20your%20endpoints%2Fcalling%20features.

Another way without logging into account and simplest way: https://support.ringcentral.com/article/Block-Outgoing-Caller-ID-From-IP-Phone-RingCentral.html

• The first solution works as advertised. Does RingCentral support a code (like *82 on many phone systems) that transmits Caller Id info for that one call only?
  • RingCentral does allow an alternate caller Id number which will be used if they detect that the lack of Caller ID will cause the call to fail. But sometimes I want to send Caller ID because the recipient may not answer the ringing phone otherwise...hence the ask for a *82 type of capability.
• The second solution doesn't work. When I dial *67 I get a fast busy signal. This occurs regardless of whether the first solution has previously been used to configure the user's caller Id to 'blocked' or 'main number'.

The first and 3rd solution works fine for me.. Not tried the second solution from online portal yet.

Not sure why *67 <number># doesn't works for you.. It works fine for me