Delete SecureCRT.SecureFX/arm64 directory

SecureCRT.SecureFX/arm64/README.MD

@@ -1,5 +0,0 @@
-# md5: e8bd4b325a78f695aefb8885d3660fdd
-```
-split -b 20m -d -a 3 ../scrt-sfx-9.5.2-3325.macos_arm64.dmg scrt-sfx-9.5.2-3325.macos_arm64.dmg.
-
-```