Please follow the steps below to remove tab color:
Step 1: Click any cell in the worksheet that you want to remove the Tab color;
Step 2: Click the "Home" tab from the ribbon;
Step 3: Click "Format" in the "Cells" section;
Step 4: Move your mouse to "Tab Color" and select "No Color" from "Theme Color" list.
Alternatively, right click on the tab name, move mouse to Tab Color and select "No Color" from "Theme Color" list.