@Manage4 US Thanks for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
Azure SignalR service is offered in three different tiers Free, Standard and premium. If you SignalR service are running in tier other than free, then you will be billed based on the base charges mentioned here in this documentation.
We don't have any option to start/stop the SignalR service. If you want to stop the billing, you can change the tier from standard/premium to free tier based on your requirement.
Also, note that changing SignalR Service from Free tier to Standard or Premium tier or vice versa, the public service IP will be changed, and it usually takes 30-60 minutes to propagate the change to DNS servers across the entire internet. Your service might be unreachable before DNS gets updated. Generally, it’s not recommended to change your pricing tier too often.
Hope this help, let me know if you have any further questions on this.