Had the same problem. Felt sorry for the bees and tried to remove in the late afternoon when it was the hottest! Big mistake! I had a small pair of plyers and mashed a few bees and still didn't get the reducer out. Really made the bees mad and got stung on both hands. Didn't use the smoker. Learned a valuable lesson.
Early the next morning when activity was very slow I went out to the hive with my fencing tool and screw driver. Pried up the box a little, hooked the entrance reducer in the hole with my fencing tool and pulled it out. Took five seconds.
Have been singing "Jesus loves me" to the bees and seems to quiet them down. No problems for several weeks now.
"A soft answer turns away wrath, but a harsh word stirs up anger." Proverbs 15:1