Don't forget you can burn Street Cred to lower Public Awareness.
Not in SR5. Since Public Awareness no longer has an automatic [(StreetCred+Notoriety)/3] component, lowering Street Cred and Notoriety doesn't matter either.
This doesn't necessarily mean that the GM shouldn't allow the characters to work hard to lower their Public Awareness, or even to not still link PA to both Street Cred and Notoriety; IMO, burning Street Cred at double the amount listed for Notoriety might do well to lower PA. Again IMO, only a really flamboyant runner (Kane) or someone who makes a point of getting their name out there, who are
trying to be famous (again, Kane, but IMO certain other 'street legends' as well) should retain a high level of Public Awareness.
Also, as people are constantly getting bombarded with new material, IMO (yeah, yeah) things like Street Cred, Notoriety, and Public Awareness should recede over time presuming they're not being constantly 'added to' - down to perhaps half their maximum level. Current and Permanent levels, as it were. Adds some more granularity to the game, I admit, so ...