2001 Protege O2 upstream sensor removal question 1.6L

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mazda protege
I've got an upstream O2 sensor connector plug on an 01 Protege 1.6L that doesn't want to release. When removing the O2 sensor plug, do you press down on the clip or pull up on the clip? Any ideas on how to pull the plug apart, it seems really tight and stuck? Thanks for any replies.
 
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83 RX-7 Gsl, 2000 Mazda Protege LX, 2011 Mazda3 Sport i
Usually I spray it down with air, push the clip together and then one good tug to pull them apart.