delay: remove unused delay_is_elapsed

diff --git a/src/delay.c b/src/delay.c
index fb49450..bcdb62c 100644
--- a/src/delay.c
+++ b/src/delay.c
@@ -65,16 +65,6 @@ void delay_init_ms(delay_t* self, uint32_t ms, delay_callback_t cb, void* user_d
     self->id = i;
 }
 
-bool delay_is_elapsed(const delay_t* self)
-{
-    ASSERT(self->id < COUNT_OF(_tasks));
-    if (_tasks[self->id].done) {
-        memset(&_tasks[self->id], 0, sizeof(struct task));
-        return true;
-    }
-    return false;
-}
-
 void delay_cancel(const delay_t* self)
 {
     ASSERT(self->id < COUNT_OF(_tasks));
diff --git a/src/delay.h b/src/delay.h
index 1922d59..9444cf8 100644
--- a/src/delay.h
+++ b/src/delay.h
@@ -12,13 +12,10 @@ typedef struct {
 
 typedef void (*delay_callback_t)(void*);
 
-// Creates a non-blocking delay. Check with delay_is_elapsed if it has elapsed.
+// Creates a non-blocking delay.
 // Limited to 10 concurrent delays, will abort if it fails to allocate one
 void delay_init_ms(delay_t* self, uint32_t ms, delay_callback_t cb, void* user_data);
 
-// returns true if time has passed. After it has returned true once it must not be called again
-bool delay_is_elapsed(const delay_t* self);
-
 // Cancel delay if you don't intend to check it until it elapses
 void delay_cancel(const delay_t* self);
 #endif
diff --git a/src/rust/bitbox02-sys/build.rs b/src/rust/bitbox02-sys/build.rs
index 0f1048a..1d91f3c 100644
--- a/src/rust/bitbox02-sys/build.rs
+++ b/src/rust/bitbox02-sys/build.rs
@@ -62,7 +62,6 @@ const ALLOWLIST_FNS: &[&str] = &[
     "confirm_transaction_fee_create",
     "delay_cancel",
     "delay_init_ms",
-    "delay_is_elapsed",
     "delay_ms",
     "delay_us",
     "da14531_handler",