Accretion disks around supermassive black holes (SMBH) are promising sites for stellar mass black hole (BH) mergers due to mass segregation and merger acceleration by disk gas torques. Here we show that a GW-kick at BH merger causes ram-pressure stripping of gas within the BH Hill sphere. If $R_{H}geq H$, the disk height, an off-center UV flare at $a_{rm BH} sim 10^{3}r_{g}$ emerges within $t_{rm UV} sim rm{O}(2 {rm days})(a_{rm BH}/10^{3}r_{g})(M_{rm SMBH}/10^{8}M_{odot})(v_{rm kick}/10^{2}rm{km/s})$ post-merger and lasts O$(R_{H}/v_{rm kick}) sim rm{O}(5 t_{rm UV}$). The flare emerges with luminosity O($10^{42}{rm erg/s})(t_{rm UV}/2{rm days})^{-1}(M_{rm Hill}/1M_{odot})(v_{rm kick}/10^{2}{rm km/s})^{2}$. AGN optical/UV photometry alters and asymmetric broad emission line profiles can develop after weeks. If $R_{H}<H$, detectability depends on disk optical depth. Follow-up by large optical sky surveys is optimized for small GW error volumes and for LIGO/Virgo triggers $>50M_{odot}$.
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