Yes
But it you need to refer to your company policy about that - the list with written warning / verbal warning per offence. If no such list exists or the transgression is not listed, then you can go straight to final written warning. We did it with our small business and it was upheld in a CCMA hearing.
Important thing is this needs to be consistent, in other words one cannot give a verbal warning today to one employee and then a final written to another employee the next day. Also all warnings (verbal and written) first require a hearing before they may be issued, they cannot just be issued. The hearing can take place as an informal one at the moment. Example is where a staff member is late and the manager ask why and gives the staff member an opportunity to give a reason. But if the manager just walked up to the staff member and handed a verbal/written warning without saying a word, then CCMA might not uphold it.
Also previous warnings for other transgressions can be used as a reason for the final written one.
(We did a lot of research on this topic a while back when we had a problem staff member. The law is there to protect both parties. Ultimately one needs to speak to a professional if this will lead to a CCMA hearing or dismissal).
EDIT: We also always contact our labour consultant for each and every warning - both written & verbal - to make sure we are within the law and within the rights of both parties.