I think you are mistaken. At least from my reading of The Stranger I remember Camus stating suicide is a cowardly act. Wikipedia[1] states Camus viewed suicide as a rejection of freedom. Also the myth of sisyphus doesn't have much to do with suicide does it? I may be mistaken. I thought it was more of an analogy to the condition of man, not so much a suggestion to commit suicide to avoid it.
Having just read Myth of Sisyphus, the first 3rd is essentially dedicated to the idea of suicide and how to process that choice in the face of "meaning".
[1] https://en.wikipedia.org/wiki/Philosophy_of_suicide#Absurdis...