I purchased a duplex in Boyle Heights, 90023, in 2013. The lot is approximately 10K sf. I was able to legalize an unpermitted two bedroom, one bath space, thus making the property a triplex.  There is a 520 sf garage that I would like to convert into a one-bedroom, one bath unit.  I did my research with the city and am able to legalize it; consequently, making the property into a quad.  However, I inherited a tenant whose rental agreement included her two bedroom, one bath unit and the detached 520 sf garage.  The property is in a rent control area and the tenant was unwilling to accept a cash for keys agreement that was in accordance with RSO rules. 

The previous owner added the garage to her contract for $350/month.  I want to offer her a rent decrease of $350 for the garage as I believe it can rent for $1,400 (Median rent on Rentometer.com).   I am seeking help from this community to find creative ways for me to negotiate for the tenant to restructure her lease agreement without the garage; she currently only has junk in there and it's non-functional (I did pass city inspection a year ago though).

Thank you in advance for any advice you can offer.