Praise be to Allah.
Delaying tawaf al-Ifadah
Yes, it is permissible to delay tawaf al-ifadah and then do one tawaf which will suffice for both tawaf al-ifadah and the farewell tawaf . But it is better to do two tawafs, one for ifadah and one for farewell.
Doing tawaf al-ifadah on the day of ‘Eid
Even better than all of that is to do tawaf al-ifadah on the day of ‘Eid, after stoning Jamrat al-‘Aqabah and slaughtering the hadiy (sacrificial animal), and cutting your hair or shaving your head. Then when you want to leave Makkah, you should do the farewell tawaf. This is what the Prophet (peace and blessings of Allah be upon him) did.
Shaykh Ibn Baz was asked about this matter and he said:
“There is nothing wrong with that, if a person delays tawaf al-ifadah and when he wants to leave he does tawaf after he has stoned the jamarat and finished everything. Then if he does tawaf al-ifadah that will suffice for the farewell tawaf as well. But if he does both – tawaf al-ifadah and the farewell tawaf , that is even better, but if he does just one and intends it as the tawaf of Hajj , that will be sufficient.” (Fatawa Ibn Baz, 17/332)