Will the generated heatmaps and recorded sessions still work even if I remove the page on my website?

Yes, the heatmap and recorded sessions will still work when you remove the page from your website.

I have deleted session recordings and heatmaps from my cloud subscription but my quota has not reset?

Heatmap and session recording quotas can not be reset by deleting samples or recordings. Quotas are only reset on the anniversary of your cloud subscription renewal.
You can check your quota usage from the billing section of your Matomo account, when logged in as a billing owner. Administration(cog icon) > Billing > Account.
To increase the quotas, you would need to upgrade to the next hits plan.

My heatmaps or session recordings are missing?

If a heatmap or session recording has been deleted by a user, you can check the user activity from our access logs when logged in as a super user. Administration(cog icon) > Diagnostic > Activity Log.

Please note that we only keep heatmap and session recordings for three months from the date of creation on our cloud subscriptions.