Can the verb to scratch mean “start from the beginning”?
Can I say “I scratched” to say “I started from the beginning”?
No, to scratch cannot mean “start from the beginning”. This is expressed by “to start from scratch”:
from scratch: from the very beginning, esp. without utilizing or relying on any previous work for assistance: he built his own computer company from scratch.
Also, beware! The verb scratch can also mean to cancel or abandon, so saying “I scratched the project” would not mean you’ve started it from nothing, but that you cancelled it.