gradual reduction

• taperingProgressive decrease in width
• declineDecrease or refuse
• fadeLose intensity gradually
• waningGradually decreasing in intensity
• diminishingBecoming progressively less

slowdown · easing · phasing out · wind-down · attrition · erosion · thinning · dwindling · ebbing · shrinking · withdrawal · weaning · stepdown · deceleration · softening · cooling · mellowing · subsiding

• quittingquit, resign, resignation, stop, end