Jeff Even wrote:

In response to the question as to whether a state legislature can repeal or
amend a law adopted by initiative (specifically, in the question, a term
limits initiative):

In Washington, the state constitution permits the Legislature to amend or
repeal any initiative if they do so more than two years after its enactment.
The Legislature can also amend, but not repeal, an initiative within that
initial two years if they do so by a 2/3 majority. Wash. Const. art. II,
section 1(c).

Jeff Even
Assistant Attorney General
Solicitor General's Team
PO Box 40100
Olympia, WA 98504-0100
voice: (360) 586-0728
fax: (360) 664-2963
jeffe@atg.wa.gov