Remove deprecated 'image' render mode option

src/ol/layer/VectorTile.js

@@ -126,12 +126,6 @@ class VectorTileLayer extends BaseVectorLayer {
      */
     this.un;
 
-    if (options.renderMode === VectorTileRenderType.IMAGE) {
-      //FIXME deprecated - remove this check in v7.
-      //eslint-disable-next-line
-      console.warn('renderMode: "image" is deprecated. Option ignored.')
-      options.renderMode = undefined;
-    }
     const renderMode = options.renderMode || VectorTileRenderType.HYBRID;
     assert(
       renderMode == VectorTileRenderType.HYBRID ||

src/ol/layer/VectorTileRenderType.js

@@ -8,14 +8,6 @@
  * @api
  */
 export default {
-  /**
-   * Vector tiles are rendered as images. Great performance, but
-   * point symbols and texts are always rotated with the view and pixels are
-   * scaled during zoom animations
-   * @api
-   * @deprecated
-   */
-  IMAGE: 'image',
   /**
    * Polygon and line elements are rendered as images, so pixels
    * are scaled during zoom animations. Point symbols and texts are accurately