There's 2 parts to it. The border and the background. Their CSS is as follows.
Border
Code:
.cb_template .cbregPlan_rounded:hover > .card:not([class*="bg-"]),
.cb_template .cbregPlan_rounded.cbregPlanSelected > .card:not([class*="bg-"]) {
border-color: rgb(250, 182, 9);
}
Background
Code:
.cb_template .cbregPlan_rounded:hover > .card:not([class*="bg-"]) > .card-header,
.cb_template .cbregPlan_rounded.cbregPlanSelected > .card:not([class*="bg-"]) > .card-header {
background-color: rgb(250, 182, 9);
}
You should be able to use those same selectors to remove it or even change its color to whatever you like.