I'd keep it, but I'm not fussed.

綺麗	17,699,590	37.3%	
奇麗	450,589	        0.9%	
きれい	17,905,902	37.7%	
キレイ	11,415,577	24.0%
----
Aozora Bunko:
綺麗     5867
奇麗     917

If rK is meant to indicate that the form isn't worth learning, I don't think it should be used for 奇麗. With an n-gram count of nearly half a million (almost spec2), it's a form that learners should probably be aware of. Also, for whatever reason, it's the only kanji form in prog and wisdom.

@@ -6 +6 @@
-<ke_pri>spec1</ke_pri>
+<ke_pri>ichi1</ke_pri>
@@ -10,2 +9,0 @@
-<ke_inf>&rK;</ke_inf>
-<ke_pri>ichi1</ke_pri>
@@ -20 +17,0 @@
-<re_pri>spec1</re_pri>
@@ -46 +43 @@
-<s_inf>as きれいに</s_inf>
+<s_inf>as 〜に</s_inf>

sense 1
綺麗な子	21917	55.0%
きれいな子	11301	28.3%
キレイな子	6663	16.7%

綺麗な人　	100016	50.3%
きれいな人	59967	30.2%
キレイな人	38762	19.5%


綺麗な花 	159938	50.3%
きれいな花	132221	41.6%
キレイな花	25716	8.1%

綺麗な景色	57995	48.5%
きれいな景色	41394	34.6%
キレイな景色	20177	16.9%

(not really uk!)


sense 2
部屋を綺麗	12575	26.6%
部屋をきれい	15049	31.8%
部屋をキレイ	19656	41.6%


綺麗にしなさい	577	12.0%
キレイにしなさい	267	5.6%
きれいにしなさい	3950	82.4%




sense 3
綺麗に忘れ	2508	29.5%
きれいに忘れ	4244	49.9%
キレイに忘れ	1698	20.0%
綺麗にわすれ	0	0.0%
きれいにわすれ	47	0.6%
キレイにわすれ	0	0.0%

(I think this qualifies for sense 3 too?)
きれいさっぱり	70139	75.2%
キレイさっぱり	22014	23.6%
奇麗さっぱり	1104	1.2%

@@ -9,0 +10 @@
+<ke_inf>&rK;</ke_inf>
@@ -14 +15 @@
-<ke_inf>&oK;</ke_inf>
+<ke_inf>&sK;</ke_inf>
@@ -28 +28,0 @@
-<misc>&uk;</misc>