Ted is right... If for any reason you needed to bring any changes the custom visual name, displayName or even visual class name , that would be done in pbiviz.json file of your project
{
"visual": {
"name": "CustomVisual", // internal visual name (should not contain spaces)
"displayName": "Custom Visual!", // visual name displayed to user (used in gallery)
"guid": "PBI_CV_xxxxxxx", // a unique id for this visual MUST BE UNIQUE
"visualClassName": "Custom" // the entry class for your visual. (By default Visual: visual.ts)
"version": "1.0.0", // visual version. Should be semantic version (increment if you update the visual)
"description": "", // description used in gallery
"supportUrl": "", // url to where users can get support for this visual
"gitHubUrl": "" // url to the source in github (if applicable)
},